Practical reason and pure reason

Since I have dealt with Kant a lot (although I am not an “expert”), I may have some insights into your question.
First of all, Kant himself says what you put in the mouth of the neo-Kantians (I myself have not encountered such a position in any of them, but you may be right).
But regarding his words, it is necessary to be precise: there are not “two”reasons in Kant, but only one and only one. The first time is pure reason (clean from the shelter of the senses, imagination, etc.) in its theoretical use and the second time is pure reason in its practical-moral use.
Indeed, practical use precedes theoretical use for the following reason: pure reason cannot produce theoretical metaphysical knowledge about the thing in itself but certainly “pretends”to do so. Kant wants to limit this pretense without giving up the underlying striving. Therefore, he not only “allows” reason in its practical-moral use to set for itself those norms (which are not theoretical knowledge or truth), but also obliges man to make such use.
In other words: for moral, not cognitive, reasons, we should focus on the practical use of pure reason. Paradoxically, he says that a more “modest” approach like this will lead us to a kind of familiarity with the thing-in-itself and the ability to escape the teeth of determinism.
Another way to describe this is to say that Kant preaches the sublimation of our most primal intellectual impulses, that is, he preaches their conversion into practical activity that does not exceed the limits of rationality.

When a dog does not attack its master but attacks someone who comes to harm its master, is the dog using pure reason or practical moral reason?

Everything Kant says applies only to subjects, especially intelligent subjects. In his view, dogs do not belong to this group. Therefore, in his view, the category of morality is irrelevant to animals.

Thanks, Doron.
I haven't been home since writing the question so I couldn't check,
but I think it exists at Herman Cohen.
I'll check and write here in a nutshell

Shalom Rabbi.
I am still perusing the writings of Herman Cohen and his friends to find what I attributed, and the thought occurred to me that in fact you yourself, in the columns you have published recently, have often dealt with the importance of democracy and giving an independent value to human rights and freedom (contrary to the common practice among the dosis who must prove this from the Talmud and the poskim, and lie in the dust of the Sifra and the Saphiri and the Mikhilot).
This is certainly not talk about practical reason as prior to pure reason, but certainly pragmatic talk about practical thinking as distinct from abstract philosophy and not exactly as its conclusion.
Seemingly, from here the path is short to also assume a principled precedence, that is, striving for abstract truth from an ethical approach (after all, we have already reached the conclusion(?) that ethics does exist as distinct from abstract philosophy and not as a result of it).
I hope I didn't talk nonsense…

I really don't see any connection to the question of practical and pure reason. And as mentioned, I also don't understand the meaning of the sentence regarding precedence, or the sentence you formulated here regarding principled precedence.

Regarding the meaning of the sentence – I will explain.
After all, we have in our brain, it turns out, an effect of pure reason and an effect of practical reason.
There may be no connection between them, and each of them can be thought of separately.
I can be a philosopher who, from an abstract study, will come to the conclusion that there is a God, who is the creator of the world and the creator of man, and that he demands from man moral behavior and/or observance of ritual commandments and/or to act according to his practical reason, a kind of religion of reason. In such a case, practical reason will be born of pure reason.
I can also be a person who is mainly interested in practice, but if I think that if there is a creator of the world, I have a moral obligation to keep his commandments, or alternatively if I think that if there is a God and he gives reward and punishment then it is very worthwhile for me to be faithful to his commandments, practical reason requires me to invest an abstract philosophical effort in order to ask myself if there is a God. (And not only that, but any abstract issue that might have a practical impact is worth investigating.)

It is apparent that different people will have different options among these, the question is whether there is an ontological precedence for one over the other.

That is, is there a necessary principled ontological priority?

I can't understand the question and don't see the slightest difference between the two options you described. Define practical, pure wisdom, and give a concrete example and formulate the question based on it.

In your opinion,
Does moral consciousness (and all practical thinking) derive / in principle need to derive from abstract philosophy?
Or alternatively,
Does abstract philosophy derive / in principle need to derive from moral consciousness (/all practical thinking)?

I don't understand the question. Can you be more specific? An example?

The simplest example there is – in the religious section, i.e. observing a commandment as a projection of a philosophical concept (there is a God, and He wants/demands that I keep a commandment) or approaching the study of philosophy as observing a commandment.

But this really misses the point of the question, because I wanted to ask whether categorical, abstract thinking from a practical/ethical approach is flawed, or possible, or even preferable

Corrected:
The simplest example there is – in the religious section, i.e. keeping a commandment as a projection of a philosophical concept (there is a God, and he wants/demands that I keep a commandment) versus studying philosophy as keeping a commandment. Is one better than the other?

But that really misses the point of the question, because I wanted to ask whether categorical, abstract thinking from a practical/ethical approach is flawed, or possible, or even preferable.

I'm done. Unless you manage to get down from the general and vague statement and provide an example and formulate the question about it.

Is the example from the religious section problematic?

This doesn't seem like an example of anything to me. It's a question in itself, and even it's not clear: Is there value in studying philosophy? Or alternatively, should the observance of the commandments be done for philosophical reasons? What does this have to do with practical or pure reason? And why are your two options mutually exclusive alternatives? And is it not possible that there is value in studying philosophy, and at the same time observing the commandments for philosophical reasons or because God wants it? I don't even understand the words I'm writing here.
What's more, you yourself said that this example doesn't express your (mysterious) point. I really don't know what to do with these questions, unless you put a concrete and clear question here, since it gets to the point, with two options, each of which is well defined.
I think, with apologies, that the fact that you repeatedly fail to present such an example implies that the question isn't well defined for you either.