My flip should arrive tomorrow (yay!) so I decided to check discord for instructions on how to replace the original SD card(s). Lo and behold there is already CFW for this new device. Installation seems pretty involved so I'll probably stick with OFW for awhile at least.

Having said all that here are the links:

Installation instructions

Early Rocknix for Miyoo Flip Download

Credit to spycat and Gamma and many thanks for their work.

Edit for breaking news:

Gamma demos bluetooth audio support and confirms controller support via onboard bluetooth.

Days later edit:

This was taken down when the dev's miyoo flip failed permanently. It's unclear whether rocknix was the cause, just a dev unit issue, or even a production hardware issue. I believe in an abundance of caution he pulled the rocknix release just in case.