Move from RPi4 to x64

[Lapineige]

And here, but it was closed

Raspberry-pi : convert to 64 bit installation? (manual way : reinstall, convert to btrfs)

Hello, Is there anyone with experience in migrating a Raspberry Pi (4) from 32bit raspbian to 64 bit ? In particular, I’m searching for a way to convert the system without reinstalling, for several reason but the main one is : I don’t want to reinstall and reconfigure all customs tools I installed and configured on this 4 years old installation… (Yes, it’s mainly for Nextcloud ≥26 versions) Any good tutorial or tips to share ? Thanks !

(if some moderator comes by…)