Eagerly awaiting any progress, willing to pay to give it a try, as far as hardware goes- I can easily fill up all the outputs. Is there still room on the GPIO for a couple I2C sensors for temp/RH and the such? You're going to give Pegasus power packs a run for their money, I suppose. I'd buy one of these over another UPBv2, no doubt.
Perhaps the biggest spec for me on this board is the 12V input to the hat- it powers the Pi, correct? Heck. YES. Much needed. Who has time for 5V when you're mobile? Too much struggle, imo.
Thanks for tackling this- it's going to be very useful. Hope you're doing well during lockdown.