I haven't touched this stuff in 5+ years, but I wonder how iNav stacks up on your list? I was about 50% of the way through a 7" FPV build with a GPS receiver based on iNav when COVID hit, and between the supply shortages and general life shift, I stopped working on it.
I fly iNav on a couple planes. I havent updated to the latest version in a couple years but i find it works great. The electronics like gps modules and sensors are insanely cheap now if you go straight from china (aliexpress) - you can get an hglrc m100 gps for about $12 shipped now.
I'm curious too; of those it's the one I have the least experience with. It is currently not an option for me, as the aircraft I would use with it uses CAN perhipherals, which iNav doesn't support.
