Hi,
a few folks have previously tried to buid (parts of) FG on lower-end hardware - so you should be able to find quite a bit of relevant info by browsing the forum/devel list archives or by browsing the wiki.
I believe, one of the more recent efforts was building a subset of FG on RPi, others have previously tinkered with Android specifically however.
So, my suggestion would be to create a corresponding wiki page and document your journey to get more people involved.
Speaking in general, it might make sense to provide patches to the project to allow FG to be build on more platforms like these, even if that should mean disabling certain portions of the build altogether (aka feature toggles) - the point being, a number of core devs are currently in the process of porting FG as a whole in order NOT to use fixed function OpenGL, and early experiments also involved simply disabling offending code in a "brute force" manner by excluding it from compilation using #ifdef macros.
For some background reading, I'd suggest these articles (in the given order):
https://wiki.flightgear.org/OpenGL#Statushttps://wiki.flightgear.org/FlightGear_ ... re_Profilehttps://wiki.flightgear.org/FlightGear_and_old_hardwarehttps://wiki.flightgear.org/Howto:Optim ... le_devicesWhile some of these articles may seem a little outdated or unrelated in scope, they are more relevant than you may think - because at the end of the day, all these efforts/people were working towards the same goal of making FG more portable, better configurable to expose more build/startup and runtime options.
In particular, Edward (bugman on the forum) has been working on this as part of his unit testing effort, specifically:
https://wiki.flightgear.org/FlightGear_Headlesshttps://wiki.flightgear.org/Cppunit_effortThere also is a long-term effort to make more and more subsystems better configurable, and ultimately, OPTIONAL:
https://wiki.flightgear.org/Howto:Reset ... leshootingTo support different types of GPUs, see:
https://wiki.flightgear.org/Graphics_card_profilesPS: Most of the log file you shared is merely reporting warnings (that are due to compiler flags), but there are few actual errors, and these would seem to be a configuration issue - if in doubt, I'd check whether your compiler can be configured to build the C++ version used by the SG/FG sources - in general, there are very few actual errors in your log - according to $SG_SRC/CMakeLists.txt, SG now uses C++17, so you will want to be sure that this is also supported by your build environment. A good starting point might be to only build the sources inside the Compositor directory in SimGear, since those templates seem to be causing most of your issues. Also, according to the line numbers in your log, you are not using the latest SG/FG checkouts ?