I have installed an aftermarket tow hitch on my 2021 x7 40i. My experience is described in this thread on the 2nd page
https://g07.bimmerpost.com/forums/sh....php?t=1824537
I use it to carry my bikes, so no towing. If you want to tow, then coding will be required on top of both hitch and wire harness installations. Not every indy shop wants to do it, and going to a dealer would definitely be expensive.
Let me know if you have any questions.