After some searching I hound it here
http://tinycorelinux.net/10.x/ (sorry I can't see how to make that a link).
I have been using it extensively for the last few weeks on a RPi3 and 3+. By default it has USB FIQ turned off that apparently can give USB problems, - Can anyone comment on what the problems are?. I never seen any, but I have not stress it, only using a keyboard, memory stick and wired network for ssh.
If FIQ is turned on it makes USB reliable but crashes on boot if an HDMI monitor is attached. As I run headless I have now turned it on.
There are not many extensions available, any copied from PiCore9 that use encryption will not run due to an updated library, so expect to spend some time building extensions. I now have the WiFi and everything I need running.
I can't comment on timescales but I expect that Bela is waiting for a fix to the underlying Raspbian problem.
Tim.