I could not get it to compile. After 2 hours, instead of holding up the release, I just released everything else. I'll keep trying but I'm really quite stuck.
Discussion
I ended up compiling it with cargo because the AppImage needs a glibc>=2.32 (i have glibc 2.31). I copied the user data from gossip's flatpak dir (~/.var/app/com.mikedilger/gossip) into ~/.local/share/gossip but when i start it, it ignores the config and shows the dialog to create a new key.
I'll stay on 0.11.3 for now until i figure out how to properly migrate my existing gossip data files.
Managed to import the private key with v0.12, everything is working including videos. The bookmarks system is great !