Foveon has awful Foss support so far. Older foveon models also require an older version of windows to run the antiquited software to process raw pics, it's maddening.

The algorithms for getting a useable image from a Foveon sensor are very non trivial from what I understand - the different layers don’t separate light perfectly into red, green, and blue bands, so there is some fancy cross layer processing you need to do.