Be prepared to change your mind…

That first install of proxmox / nextcloud / whatever, will be removed and you will setup something else - this is a good thing.

So, you’ll probably want to get onsite backups sorted early… even if that’s just cloning to an external drive first.

IMHO don’t consider a NAS as your server - keep them separate. A cheap ebay PC with a couple of drives is fine.

And, if you’re considering home automation you will want a UPS