For the older ones with Broadcom WiFi I was able to get stock Ubuntu working great by following this:

https://askubuntu.com/questions/55868/installing-broadcom-wi...

Not sure about the newer ones.

Gathering this information and putting together a distro to rescue old Macbooks from the e-waste bin would be a worthwhile project. As far as I can tell they're great hardware.

I imagine things get harder once you get into the USB-C era.