Well, I was bored last night and ended up converting my heavy 5" drone to INAV to try playing with the navigation modes that it offers.  I went through all that work converting it and my DJI goggles to find out navigation modes require not only a barometer but a compass too.  Makes sense although I figured Altitude hold would at least work...  Nope.

Unless of course there is something I'm missing?  I think I searched enough to learn that I'm out of luck though?
it would be fun to experiment a little with those modes and learn that mission tab in INAV - looks interesting.  

I debating whether I should just roll back to betaflight or leave INAV on it and buy a GPS+Compass module...

Getting a compass to work properly on a 5" quad can be a PITA because you need it far away from other components on the quad which means you usually end up having to mount it on some kind of tall stem type of mount which then makes the GPS module and mount extremely vulnerable in a crash.

I've never personally used INAV and have no plans to do so because I don't fly any quads that are larger than 5". It seems to be more useful / appropriate on larger long-range quads (7" and bigger) or wings if you want to make use of the autonomous features it offers.

There are a lot of what I think are really cool features that INAV offers, but I think I am agreeing with you on this 5".

I want to explore long range I think it would be fun. Maybe a fixed wing would be the better route for my long range mission...

Im on that path now, got the mateksys m8q-5883 to my 5” quad I flashed with inav the other day..

Eager to explore the possibilities, planning on installing a lidar next??

Happy flying!