Warning: talking out of my butt a bit so take with a grain of salt.
I wonder if you could look at micropython. You could implement a unix like world on top of micropython then use micropython as the layer where a normal os would be.
It would be miserable and likely impossible to be fully unix compliant but could be a fun thing to play with. I would be amazed if it ever somehow could run native unix binaries.
The fact that they changed the name to Azure Linux still upsets me. I get upset easily.
We use it at work. Seems mostly fine and similar enough to old CentOS and RHEL.