alt Hacker NewsThat doesn't really happen in the embedded space.
Even if the core was supported just fine, all of the IO mux stuff is pretty much guaranteed to be different even with the same chip in a different package.
You're looking at explicit support for each chip.
I worked on a project porting from an STM32L073 to a STM32U073, which management were assured was a complete drop in replacement. Well, it was only in the sense that you could drop one onto the old PCB. It became a running joke how many software compatibilities we ran into. My favourite was an "LCD clock disable" bit became "LCD clock enable". And this was for a specifically chip designed to be an easy replacement.