Gas Buddy finds you area gas stations and the best price (or worst if that's what you want) but can not tell you if they are RV FRIENDLY.
FOr the most part the big Truck Places (Flying-J/Pilot Loves and T/A) are RV friendly (Few exceptions and Flying-J's also generally have special RV lanes with both D and G. and RV parking overnight (And a Denny's as opposed to a Fast Food place like Arby's or Wendy's) Generally (not always)
MY PILOT will find Flying-J and Pilot
Loves has an app
And I suspect TA does as well.
I use 'em when I do my migration trips.