There are a couple of problems with environment.d - it cannot be made idempotent, and can't splice into the middle. These shouldn't be a problem since it runs

There are a couple of problems with environment.d - it cannot be made idempotent, and can't splice into the middle. These shouldn't be a problem since it runs early enough and should be controlled by a single sane party, but makes porting a pain. I don't understand what problem your [2] link is referring to, since the whole point of systemd user sessions is that it happens before graphical stuff.