Multiple ssds?s

[John]

Separate ssd for nextcloud app?

That would have been awesome, but unfortunately the Raspberry Pi is too humble to power two drives simultaneously and the result is a very unreliable experience. However, as we move Bitcoin Core to the app store in the future, you could then set up a dedicated Umbrel for Bitcoin Core and another for Nextcloud without worrying about Bitcoin Core taking ~400GB or so of the disk space.