What about BeOS ?
OK, point.
Not very likely, what if the BeOS API emerged as "the standard" on Linux?
It would not solve the ABI problem, but it would give at least an opinionated end to end API that was at some point the official API of an OS. It has some praise on its design too.
It was more about everything since the Amiga being a regression. BeOS was sometimes called a successor (in spirit) to the Amiga : a fun, snappy, single-user OS.
I regularly install HaikuOS in a VM to test it and I think I could probably use it as a daily driver, but ported software often does not feel completely right.
AmigaOS was the pinnacle of personal computing OS design. Everything since has been a regression. Fite me.