The hotstrings feature is also present in Linux, where they are known as compose sequences. The default compose sequences can be found in the Compose files under /usr/share/X11/locale and you can also have custom compose sequences in ~/.XCompose. Some of the compose sequences make use of a special Compose key (written <Multi_key> in the rules). You may need to go to the keyboard settings to enable the compose key.

https://en.wikipedia.org/wiki/Compose_key

Edit: by the way, these compose sequences also work under Wayland. The only hiccup I found with wayland was that include directives didn't work so I had to put everything in a single file.