My first idea was to use the Gitea instance of the Free Software Foundation Europe, but T&Cs strongly encourage only projects with direct relation to the FSFE activities, so personal projects don’t seem welcome.
The first-party Gitea platform seems to be in risk of becoming for-profit.
I host it on a raspberry pi with 2 GB RAM for myself. The only challenge with it is because I do hundreds of repo mirrors, basically a local archive of public repos on other code forges that I found useful to have