So I use a keyboard layout (Irish) from a country where this a need some people have but not frequently. There is the compose feature, but it's located in the button underneath escape (labelled ` ¬ ¦), not overloading single quote.

The one issue with that arrangement is you run into video game server admin/modding tutorials and the like and they describe pressing "~" for the console, and it's hardcoded to the keycode and doesn't consider the keymap, so it's actually looking for that button, except getting a literal ` requires a double tap of ` rather than all the UI elements telling you it's ~.

Oh and quoting code blocks in markdown can be kind of annoying. Or inline variable names that start with a letter that supports the accent.

But I think I'd take those limitations over losing single quote.

ctrl-shift will switch back and forth between selected keyboards in windows, so you can keep the keyboard in ENG US most of the time (allowing you to use the ' shortcut in Firefox), and use ctrl-shift to switch to ENG INTL when needed.

There's a variant of the US layout called altgr-intl where instead of making ' a dead key you can do RightAlt-e for é.

Is that literally the same character for both? On my layout `e leads to è whereas alt-gr+e = é. é != è in many languages.

janus24 specified "é (' + e)". That's neither ` nor è.

Not all languages that use é have a use for è.