Random thought, so I'll keep this brief.
I've got two Nexus 10's here that are in great condition and I'm no longer really using them. It occurred to me that they can run armhf code (e.g. Ubuntu Touch used to be thing that could run on them, also postmarketOS runs on them).
Ubuntu MATE has an armhf build for Raspberry Pi, so that might be a start... and it would seem that there is still a kernel on launchpad for this very tablet (manta is the codename for Nexus 10)...
How crazy (or easy) is this thought?
p.s. I've got plenty of experience loading alternative OS's onto these tablets, luckily Google made it practically childsplay to load stuff on just using the "adb" utility alone.
Additionally I'm prepared to part with one of these tablets if it helps development.