I'm not sure if they're really "in business" as such; it gets some very occasional updates for new kernels (last release: 2019), but that's about it. See e.g.: http://ossnext.trueinstruments.com/forum/viewtopic.php?f=16&...

With ALSA, Pulseaudio, and now Pipewire there's not much point really; maybe it's better but that ship has sailed, on Linux anyway. It's become VHS vs. Betamax-kind of lamenting.

4Front seems to be working on https://www.truepianos.com now; though that one's not open source and no Linux version either.