Reading through the comments, it seems like you’ve got ydotool working, but it may not have all the capabilities you want. I created a tool that seems like it could do everything you need, it has a couple of prerequisites, but it runs as a python script and doesn’t require super user to work.

If you wanted to give it a go, I’d be happy to help as much as I can; I use it daily on Debian 12 with Wayland, so I’m pretty confident it should work for you on Ubuntu. Admittedly, it’s still rough around the edges, but it can definitely handle mapping ‘Alt + E’ to type an email address.

https://gitlab.com/sincere-untimely-yesterday-group/custom-input-remapping/-/tree/7d64cfd2cb70c5acc19ba7536b91f9558e69b9ce/

I’ve been running three of these for about the same length of time - two things surprised me, but both are documented in their manual. First, the working temperature is -9.9℃-60℃/14℉-140℉, so if you plan to use one in an environment colder than ~10℃, the readout will flatline. Second, they use a CR2450 battery, which is a little more difficult to find where I live than a CR2032.

Neither of these are criticisms, just things I wish I had noticed sooner.