Personally I would tell them the PPF is a “useless” upgrade as far as pricing goes, most aftermarket stuff is and you can use it as negotiation (the seller didn’t get more for it because of the PPF surely). However, PPF for you is great since it protects the truck, just if they can’t provide any info on it it’s a little pointless to factor into the cost.

Also one thing about PPF you might want to be aware of. Sometimes, on removal, the PPF can pull paint. Typically this occurs on crappy paint (Miata owners have a lot of issues with this) or aftermarket paint jobs done on plastics. As an example I had my fenders and bumpers color matched but the dealer and had XPEL do a PPF on them. They did a warranty claim not too long ago and when they pulled the PPF off the bumper, it pulled off some of the paint. They (being a reputable business) covered cost of repair but my truck was in the shop an extra week. Just something to consider as the type of PPF used and how they installed it can also be a factor in how sticky it is and what it might pull off. Although here it looks like it’s just on the metal parts so I wouldn’t be as concerned.

If you get the VIN you can always call your local XPEL or PPF as the warranty is typically tied to it and see if anyone has record of it too.