Things are progressing quickly — I was able to generate a (mostly) working SD image and started my regression testing. I have shared it with one other person (for initial feedback) and will make this available for early (volunteer) testers soon. For those of you that already use the CoCo-Pi, things will be quite familiar.
As a reminder, this new 64bit version is for RPi4 or RPi400 users only. RPi3 support is not something I am targeting at the moment.