I needed to boost the memory from 8GB to 16GB for Final Cut, get rid of the SSHD in favor of a 500GB Samsung SSD.
It went well! iFixit's super great guides did help me a lot!
You can just lift the power supply, you don't need to fully remove it. Keep all screws in order because there are a hole bunch of different ones. Be gentle when removing the connectors on the logic board because they are easily ripped.