I can see there are some "source code" downloads for singleplayer and holomatch, and a developer kit.
https://www.totallyef.net/downloads/These seem to be thought for creating mods/missions, not a GPL thing.... and without the engine part....
And there is this ioquake3 engine fork which should work with the holomatch:
https://github.com/UberGames/ioefSo, at least for the holomatch part, in theory something may be possible (although the result would be more similar to the quake3 ports than OpenArena port, at least license-wise). But I have no idea if Pelya may be interested on it. It's some time I don't see him around here...
Maybe you may try to contact the authors of the various quake 3 engine ports from Play Store, maybe one of them may be interested...