Username changes are coming to Loops, and later Pixelfed this summer.
It's quite challenging, but a necessity since Loops supports Sign in with Apple and it generates a random username.
To prevent federation breakage, we will keep old usernames as aliases, and limit changes to 3 times per year, once per month.
Loops doesn't use usernames in activity urls, so it won't break those.
I am also working on a FEP for this!
