Any idea on which kernel version they settled on for Ubuntu? Last time I checked they were vacillating between a 4.4 and a 5.x Linux kernel. I'm specifically Interested in the re-written 5.15+ USB Audio stack that provides pro-audio USB support, and in the new GPIO driver system, which would provide a path to next-gen GPIO support (both available on Raspberry PI OS and Raspberry PI Ubuntu).
I've been given to understand that Android can run on very ancient kernels, but there are monstrous complications with porting android-compatible Bluetooth and Wi-Fi stacks to modern Linux kernels due to lack of support by chipset vendors other than Broadcom.