Hello, as the macOS 10.15 does not support 32 bit apps, is there some plan or way how to compile/run simutrans natively there? SDL2 seems to be 64 bit so it should be possible to run simutrans natively in 64 bit mode?
It is up to someone with MacOS and a 64-bit compiler. The core developers (primarily) use Windows and Linux. Apparently, cross-compiling for MacOS is difficult or not supported. The nightly site doesn't offer any MacOS builds at least.
The last several releases have been natively compiled 64 bit.