impurity

I am trying to understand a little about the subject of impurity and purity, from what I have managed to read in several articles, impurity is not a bad thing in its essence and we have no interest or need to purify ourselves unless we are going to the Holy Place.

But all these articles that I have read seem to contradict the halakha when talking about priestly gifts, because there, as I said, there is a need to always remain pure.

And then we talk about the difficulty, the difficulty is then what? It sounds really impossible if we today have difficulty with the halakha. What is said with the laws of impurity and purity, this sounds impossible to implement, that is why I am asking. Is it possible that I do not understand the laws of priestly gifts well and there is a way where there is no constant need to maintain purity?

And also, if you have the Rabbi's page, I will bring a question I saw on the Internet that is very nicely formulated in my opinion and manages to ask well about the difficulty, I would be happy if you would address it:

“The day after the war” Shabbat in Jerusalem with Rabbi Haggai Lundin 055-2901011
Yeshiva
That's what the Internet is for

“The laws of impurity and purity seem very difficult to apply, (for example, taking a bed or sofa to the mikveh)
It is burdensome (the need to think every moment about what you are touching),
And involve great discomfort. (A situation in which impurities that come out of the man's or woman's body are not their private business)
For example – A situation that by its nature may be very common – Seder night when the woman shakes – She must be careful not to touch the food (and therefore cannot cook for the holiday), and if someone accidentally touches her or the chair she is sitting on, he cannot continue eating the Passover sacrifice (even if he immerses himself).
The question is twofold –
A. Are these her ways, the ways of pleasantness?
B. How can one hope for the building of the Temple, and with it a return to all the laws of impurity and purity?”

A. There are many things in Halacha that are not pleasant. And is a bastard a pleasant? And stoning a Sabbath desecrator?
B. Don't wish. I assume/hope that when we experience this situation we will understand how difficult it is and how to deal with it and also why all of this is important.

The arm for the cheek and stomach and the beginning of the gas do not need to be kept pure.
Donations and tithes were either given once at the end of the agricultural season or given when the fruits were not yet ready to accept impurity.
The separation of challah is more problematic because it is more daily, but even there it is actually possible to separate challah in impurity (and burn it instead of giving it to the priest) or to divide the dough into small portions. See Mishnah Challah 2,3