My P6 is matte, but when I asked MMC whether I should have the vulnerable areas covered they said "don't do it, it changes the paint colour, we tried it once and took the film off again".
That is interesting.
PPF has come on a long way since it was first used on cars. I remember the early installs I had done yellowing over time and looking awful.
My most recent experience was with XPEL, having had it professionally installed on a few panels on a previous vehicle. Once more, I have found it to be excellent.
I assume that the concerns regarding installation to matt paint would be that you'd have to use the clear film, which would inherently create a gloss finish. If PPF is important to you, and for future reference, if you know you wanted a matt look, imho, the best option is to choose a vehicle with standard paint and then have Satin film installed over it - it creates a matt look, with a protective finish and can be removed at time of sale if the new owner doesn't want it.
It would be interesting to speak with a professional about installing over Matt paint. I know it can be done and I've seen some excellent results. I've never asked if they use Satin PPF but perhaps that is how the keep the matt look.