Its hard but rewarding, and perfectly doable given you want to do it.

Note that there are a few mandatory requirements for a port to be feasible, like unlocked bootloader and vendor sources available for kernel.

As newby, you also want already existing ports to start from.

Also, some powerful hardware to build on (32+gb ram, 10+ cores, 100+GB storage).

Also older (up to A11) can be real removed, after A12 things are improving a bit.