There was a fediverse solution upcoming a year ago.

Don’t know if it was endurian https://github.com/joaovitoriasilva/endurain

Edit: it was https://docs.fittrackee.org/en/index.html

I've been using FitoTrack recently: https://codeberg.org/jannis/FitoTrack

Available on the AppStore and F-Droid

Tracking and logging/history and statistics works flawlessly for me so far, the rest of the app is quite minimalistic, but I like that, not every app needs to be a bloated social media network imho

Don't think there's any self hosting possible or rather necessary since it's all locally anyway as far as I see but it has an option for exporting the data and creating automatic backups

I'm running Geoactivity Playground on top of my Strava, which really works great. It also would work if you kick Strava into the bin and just feed it GPX files

https://martin-ueding.github.io/geo-activity-playground/