From https://nodemcu.readthedocs.io/en/dev-esp32/
the firmware can now be run on any ESP module
Apparently the modules are not considered firmware as many are completely different.
Example: wifi on esp32 does not have wifi.sta.getip() but uses wifi.sta.on(). NTP vs TIME is totally different as well.
So, what are suggestions to maintain a single codebase or is that not even practical?
We have agreed on a plan to merge the two code bases. A number of preparation task have either been completed or are currently being worked on. As (developer) resources are scarce it will take us a while to get there.
Apparently the modules are not considered firmware as many are completely different.
One doesn't contradict the other. It's just that currently there are two different firmwares for the two hardware families.