Gregory's Server
I guess the EURkey layout (at least on Windows) has AltGr+m to switch to an extra layer and and then the digits give you superscripts and the shifted digits give you subscripts.
Possibly this works only for Windows.
https://eurkey.steffen.bruentjen.eu/download/windows/1.3/eurkey-layout-complete.pdf
I switched to EURkey on the Debian laptop, too. Unlike Windows, Sway and X11 support Caps Lock as the Compose Key. EN Dash is Shift-Alt-7 Shift-Minus. I'm learning to love it, haha.