[bityard]

All of my important files get saved to a NAS on my network. It's just a raspberry pi with a big disk attached. That is backed up nightly to another raspberry pi with a big disk. That is then backed up off-site to another raspberry pi with a big disk, except that one is encrypted.

Yes, it's pis all the way down.

Nextcloud is fine but I only use it for the calendar and file sharing, I don't want ALL of my data spread across portable devices. For one, it's too much data and secondly, there's the risk of a device getting lost or stolen.

Your data isn't locked into Nextcloud, you can always switch to another system or pay for a hosted Nextcloud instance.