I had third-party coverage on a previous vehicle, purchased from PenFed (the entire process was horrific and took weeks to complete, as PenFed is inept at absolutely everything they do).
https://www.penfed.org/auto/extended-warranty
I checked with my regular service advisor at the dealer before I bought this, and was told that customers (at least the ones who understand that oil changes and dental x-rays aren’t covered) are generally happy with it and the dealership never had problems getting claims paid.
Speaking of claims, I never had any, so I ended up getting back about half of the $1,500 when I sold the car.
That may sound like a good outcome, but it really means that I spent $750 in exchange for absolutely nothing, which is how these products work.