Thank you for your help :-)
Reinstall from scratch is getting better : i guess i had encoding problems choosing locales according to my location France.
I said "Yes" and now i just say "No" and i don't have error with "sudo apt update".
About Kodi, i launched it once from login screen, choosing Kodi-GBM with my main account user/password. I got menu screen but impossible to interact : keyboard/mouse not working anymore.
After reboot, i'm now stucked at the Kodi splash screen. No menu.
A sudo reboot from Putty console took a moment to effectively reboot the Rock64, and no more Kodi menus appearing...
2021-02-09 21:47:44.903 T:547990247008 ERROR: DBus error: org.freedesktop.DBus.Error.ServiceUnknown - The name org.freedesktop.UPower was not provided by any .service files
2021-02-09 21:47:48.920 T:547865369984 ERROR: SQL: [Epg12.db] SQLite error SQLITE_ERROR (no such table: version)
Query: SELECT idVersion FROM version
2021-02-09 21:47:48.957 T:547865369984 ERROR: Process error processing job
So i had a look at ~/.kodi/userdata/Database/ and renamed Epg12.db to Epg12.db.old
Now, lauchning Kodi, i got a Dbus error in log https://postit.ilinux.fr/?02830bec8bcc36d9#2QAW5vaRzKjxNjPgxXGGfuWsr8TrjEnpE3AFobo4mQjb