Thanks btw for saying clearly that BIO is not suitable for DVI output. I was curious about this and was planning to ask on social media.

I've done some fun stuff in PIO, in particular the NRZI bit stuffing for USB (12Mbps max). That's stretching it to its limit. Clearly there will be things for which BIO is much better.

I suspect that a variant of BIO could probably do DVI by optimizing for that specific use case (in particular, configuring shifters on the output FIFO), but I'm not sure it's worth the lift.