Thank you so much for your feedback.
I think the first step on ATtiny compatibility can be ATtiny85 with a decent port on wiring. (I think will work also without external oscillator using only internal PPL clock tuned to 16mhz).
I am thinking to open a wiki defining the standard to enable people like you to build easily an implementation for a still not compatible device.
Why don't you open an issue on github and we will all speak together there :)?