The Rambam's Roots for the Counting of Commandments

Hello,
I saw that you have dealt extensively with the subject of the Rambam's count of commandments and the roots of this subject. I will admit that I have not gone through everything you have written on the subject. With your permission, perhaps you could address a question that I have had for several years.
Despite the roots that the Rambam wrote to explain why one mitzvah is included and the other is not, I feel that the root Tu that stands at the base is missing and it was not stated.
According to the rules of the Rambam, I understand that if there is a deed and a lat on the same mitzvah (such as Shabbat), both must be listed.
I can't understand why there are passages in the Torah that are counted as only one mitzvah, such as: the law of the impurity of a dead person, the law of leprosy of a garment…
On the other hand, if we take the Pesach sacrifice as an example: "(a) To slaughter the Pesach on time. (b) Not to sacrifice it on leaven. (c) Not to let its remains remain. (e) To eat the Pesach meat on unleavened bread and bitter on the night of the fifteenth. (g) Not to eat it raw or boiled. (h) Not to take any of the Pesach meat out except for the group. (i) Not to eat it as a convert. (j) Not to eat it as a resident or hired worker. (k) Not to eat it as an uncircumcised person. (k) Not to break a bone in it. (k) Not to leave it until morning. (k) Not to leave the meat of the fourteenth celebration until the third day." Why is this not a single mitzvah, "the law of the Pesach sacrifice"?

If I may, it seems to me that the Rambam (like other mitzvot enumerators) is walking a fine line. On the one hand, the Sages state that there are 313 mitzvot, no less, no more, and on the other hand, there are countless places in the Sages where it is clear that two details of a mitzvah are considered two mitzvot. Thus, the mitzvot enumerators had to expand in one place and shorten in another. The Rambam outlined a complete system of where to expand and where to shorten, but this basic root is missing, which is the foundation of the fact that there are 313 mitzvot and there is a tradition of the Sages regarding quite a few of the mitzvot. I think there is a hint of this in the second root when the Rambam says that one should not enumerate mitzvots that are taught in the 13 Midots, even though the Sages indicated that they should be enumerated (as in the case of the daughter's nakedness, a good example of this).

If you have addressed this in your writings, I would be happy to see a place for reference.
Good afternoon