How migrate nextcloud pi to 64bit on Raspi 4?

Hello there,
how can I upgrade my nextcloud pi installation (installed mid 2020 frequently updated to actual version) to the new 64bit version. I found a upgrade-thread but it relies on that data is stored on an external device.

Is it possible to simple do a data-backup out of nextcloudpi then install the new image on the SD-card an play the backup back? Or are there any gliches doing that?

I am running a Raspberry 4B 1GB and use nextcloud only as sync-server for calendar, tasks and contacts between my Mobile phone, tablet, PC and Notebook.

Thanks for help and advice,
Zusch