My car came missing half of it. is it recommended to reseal the windshield and do the trim at the same time or can i just drop my trim on without doing anything else crazy

The trim is just that. Cosmetic. I would not pull the windshield to do that unless you had some reason (you can see a leak?).

You will want to check the clips that hold the trim. If they are missing you would need to pull. I have yet to get one in without.

I do have the individual pieces or sell as a set.
https://914rubber.com/chrome-windshield-molding-set-1

Just let me know if you want individual pieces.