Greetings!
I've had PPF (both coating-infused/topcoat STEK Dynoshield and 'regular' XPEL) on cars and have had them wearing both PPF-specific coatings and 'regular' coatings. My thoughts, in a nutshell are that while PPF-specific coatings *may* have once been beneficial for a variety of reasons coatings have evolved enough that a PPF-specific coating really isn't necessary. When I was at SEMA 2 or 3 years ago I specifically asked a mfg rep for a company that produced both PPF-specific and 'regular' ceramic coatings what the difference was. His reply indicated that the primary difference was ease of use with the PPF-specific coating given that if you make a mistake coating PPF, you ain't polishing out that high spot like you would be able to do with coating on paint.
First car done fully wrapped with STEK Dynoshield and coated with PPF-specific Kamikaze Film Surface Coat. Did OK for 2-3 years driving daily April thru October; picked up some bonded contamination to the point I had to clay it before coating it again with Kamikaze ISM 3.0. The car has, overall, done better with the non-film specific coating leading me to believe that PPF-specific coatings are not quite as 'muscular' as 'regular' coatings even on PPF which generally provides a lesser lifespan than on a painted surface; coating just bonds better to paint, especially on a topcoat-type PPF.
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Second car was completely wrapped in XPEL PPF and coated with a single layer of Kamikaze Zipang; this combination was the gift that kept on giving on this daily driven car, 365 days a year in Central, OH. Frankly, I was surprised how well it held up over 4 years, 40k miles. While I did hit it with either Kamikaze Over Coat or POLISHANGEL Cosmic Spritz after a wash every month or two between April & November, that thing would clean up like new even after not getting washed for a month or two in the winter. It was still doing great when I sold the car in August of 2025 and picked up the BRZ.
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Third car just got XPEL PPF on front bumper, rocker panels and that little accent panel/vent behind the front wheel. I coated the whole thing (paint & PPF) in Kamikaze Zipang because, well...if it ain't broke, don't fix it. We'll see if it does as good as it did on the Cayman.
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For me, it always pays to coat a car with a dedicated coating as it lets me ignore it to some degree (especially in Winter) and still have it look amazing when need be...and with as little ongoing effort as possible. It could be that a spray sealant might do you just fine if you go that route; I kinda prefer to do the most I can up front as far as protection and then ride the goodness as long as I can w/ minimal effort.
TLDR: Nope, I don't believe PPF-specific coatings are necessary (anymore, they might have been at one time), find a coating you like and coat the whole car, PPF & non-PPF areas. That said, I have not tried every coating in the world so there are always exceptions to the rule but ss Mike Phillips said, "Find something you like and use it (often)"!
Hope this helps a bit and feel free to circle back with and additional questions!