[rwstout]

On my Pixelphone I found that when I only activate Nextcloud integration (and log in), Mobilesheets only shows the local files after selecting 'Sync with a folder in the cloud'.
It shows an error message: 'No permission in <Nextcloud folder>'.

After I also activate Google Drive or OneDrive, Sync to the cloud shows the folder icon.
Pressing that folder, MobileSheets shows the activated cloud services.
When I select Nextcloud, it will show the shared Nextcloud folder and I can select it.