So I bought a Raspberry Pi 4 Model B with 8 GB of RAM, flashed the card
with Ubuntu 20.10 and installed FlightGear 2020.1.3 right from the Ubuntu
I get around 15-25 fps with the default renderer which is pretty nice.
However the audio is slightly distorted and it is so from the digital output
of the HDMI port so it's not like any poor quality analog audio circuitry of
the Pi itself causing the issue either.
Cool, I have a wireless Microsoft keyboard with a trackpad connected to it so it’s kind of like the Pi 400 as well. Anyway, that small fix helped with a lot of audio issues including playing YouTube videos.