I'm de-Gooling myself, and a few months ago purchased the following:

- Synology DiskStation DS720+ - Seagate 4TB IronWolf Pro - APC Smart-UPS SC 450VA

I'm genuinely happy with it, the Synology "OS" (or w/e) is pretty good. Honestly, I just wanted photo backup, and their "Moments" photo software really isn't too shabby.

Now, if someone could help me battleproof it, that'd be wonderful. I've setup a cron to turn it off at Midnight, just so I only use it when I need it. Hearing about those 0days affecting those other NAS's makes me super paranoid about self-hosting all my stuff, so until then it's off until I need it

Depends on how technical you are, how much data you have, and how much you like to tinker.

Buying an appliance off the shelf is usually going to have limitations. I built my own personally, using a pile of WD reds and an old i7 that was destined for disposal. This is optimal for my use because I can expand it if I need to, I have full control of my data and appliance, and it's really zero maintenance once it's set up.

If you want to set it and forget it, get a QNAP or Synology. If you want to tinker with it, build your own.

You still should backup your NAS to the cloud per the 3-2-1 backups strategy (3 copies of data, 2 types of storage, 1 offsite copy). Synology has an app that can do that for you. If you're stashing away a lot of data on your NAS the cloud storage fees won't be too much cheaper than BackBlaze.

If backing up my synology to Backblaze what's the best practice to ensure full end to end encryption. I do not want backblaze to have any way to see my files (I'd probably be ok with filenames however)...

Arq backup

You can save a lot of money if you buy a couple extra harddrives, make a copy and store it with your friends/family. As a bonus, less likely to get the NSA involved.

this was my thought instead of cloud backup

I don't care so much to lose the most recent few months. Can store some extra drives at a family members house and swap them out whenever I go to visit.

I would assemble your own using FreeNAS/TrueNAS or buy a TrueNAS system that is already built for you. Having a full FreeBSD based system with modern ZFS is much more robust and does not come with any restrictions.

I personally built a NAS and use unraid on it along with (dockerized) resilio sync, and it works great for my purposes of local backup from multiple sources.