Hello, I have seen similar somewhat old questions ( here / here also )
However, I would like to know if currently with the version of FarmBot OS 15.4.6 that can be used to build a Genesis 1.2 that uses the combo Raspberry PI + Arduino Mega + RAMPS 1.4, there is compatibility of Raspberry Pi 2 / 3a+ that have 512 Mb of RAM.
It looks like you answered your own question, in one of your links. Though raspberry Pi 2 is not listed on the firmware download page. Maybe try the firmware for the Pi 3. I mean try it hook it up to the Internet and see if you get the network configurer to come up. Though to be honest I would shoot for a 3b minimum, I don’t see a pi2 being strong enough to run well.