How does someone like me, a PhD candidate who has a background in Human-Computer Interaction, contribute?
Start a blog where you get users to try and complete a task on a stock Linux install, and write about it.
"Given a stock Debian XFCE install, users were tasked to connect their Airpods pro. Here's what happened"
(Even doing this for Lemmy, I.e. "find a community about birds", would be insanely helpful)
A blog like this would help give focus for developers on what needs to be improved, in every part of the stack!