@danderson@mike The most recent iterations move away from the serial interface for IO, giving you a clock pin, reset pin, 8 inputs, 8 outputs and 8 bidirectional pins available when your design is enabled. Sounds like 66MHz potential max clock rate: https://tinytapeout.com/specs/
The main limitation is that there's not really a simple path to getting your design back in quantity. Very cool to actually be able to get a design implemented in silicon, but it's pretty much just a single prototype.