When I used to have a personal macbook that I got to keep after an old internship, I even was able to find instructions online that helped me split the SSD between Linux and MacOS, with filevault still working on the MacOS partition and full disk encryption through LUKS like normal on Linux. It did require temporarily turning off filevault and SIP while doing the partitioning (and when setting the linux partition to boot by default, although that's not required by any means), but once the setup is done, it works fine after turning it back on.