I have a Dell 7040 SFF, with 32GB of RAM.
It has:
- A 1TB NVMe drive
- A 1TB SSD
- An external USB HD (2TB?)
I let Cloudron have the entire NVMe. My Nextcloud instance is on the NVMe. However, I currently do not expect to have more substantially more than 200-300GB of data in Nextcloud.
I run backups to the internal SSD.
I have a cron job that rsyncs (or similar) the backups to the USB drive. The USB drive is mounted using its drive ID, so that it always appears at the same mount point.
There is also a process that pushes (monthly?) my backup to Backblaze.
I probably have too many layers in the backup process, but I had the USB drive around, so I plugged it in.
For network, I run a Protectli box with OpnSense as my firewall. That is not a trivial path; you will have learning to do, if you go that route. I am paranoid, but at the end of the day, @humptydumpty is right: you should be able to configure your cloudron to be as secure as anything you would be running on a VPS.
The only difference, really, is that if the machine at home is compromised, then someone will be inside your network. But, they'll probably be mining bitcoin anyway, and don't care about the rest of your network.
Hopefully that helps.
(If you're trying to store huge amounts of data, I would question whether Nextcloud is your best approach, and give consideration to having a dedicated NAS or similar (which... could run Nextcloud), but you will want to consider using a different disk configuration to support multi-terabyte configurations (I think).)