> Now imagine doing that same thing for every system you're programming on.
As a matter of fact, I already do, the XCompose way.
yadm clone /path/to/dotfiles/repo.git¹
As for the vim way, why would I use a system without vim²?
> And then imagine having to do it for a million different symbols.
I don’t know other symbols as useful as this, but sure, either of my solutions scales fine (`yadm clone` shouldn’t get bogged down by any repo smaller than the Linux kernel’s). My system's /usr/share/X11/locale/en_US.UTF-8/Compose already has a section for APL’s symbols out of the box.
¹yadm is dumb by the way, any symlink manager + git/hg is probably better
²As it so happens, I do: because vim is bloat and https://sr.ht/~martanne/vis/ fits much better in the ramdisk my OS always runs in — but I’d bet 99.99% ±0.009% of programmers install their OS on an HDD/SSD and don’t care.