Could it be the next engine for Zynthian?
They offer free Linux/RasPi version armhf & amd64 binary files:
Not drop-in ready.
I was giving a try and i really like it, but in its current state it’s not possible to integrate it on zynthian. The standalone doesn’t seems to support jack audio, so the only path would be VST/VST3, what is not currently supported by zynthian. Perhaps it’s time to rescue the Carla engine and re-add VST support.