How about a truly open groovebox? Out of the box, it's already a powerful sequencer with multiple engines. Then, customize Engines, even Apps, with a free and open SDK and GPLv3 firmware. It'll run Doom if you want. And a lot more.

499EUR incl. VAT. Tons to cover here, so here we go:

https://cdm.link/dadamachines-tbd-16-a-groovebox-thats-compact-capable-and-open-by-design/