I run similar (gitea, scrypted+ffmpeg instead of frigate, plex instead of jellyfin) plus some Minecraft servers, *arr stack, notes, dns, and my VM for development.
It's an i7-4790k from 12 years ago, it barely breaks a sweat most hours of the day.
It's not really that impressive, or (not to be a jerk) you've overestimated how expensive these services are to run.
Video is usually offloaded too to the igpu on these. I have like 13 vms running on a AMD 3400g with 32gb
Fair enough. How much RAM though?
16GB would be plenty. I've got like a dozen services running on an 8GB i7-4970 and it's only using 5GB of RAM right now.
If you're running ZFS, it's advisable to use more RAM. ZFS is a RAM hog. I'm using 32GB on my home server.
ZFS doesn't really need huge amounts of RAM. Most of the memory usage people see is the Adaptive Replacement Cache (ARC), which will happily use as much memory as you throw at it, but will also shrink very quickly under memory pressure. ZFS really works fine with very little RAM (even less than the recommended 2GB), just with a smaller cache and thus lower performance. The only exception is if you enable deduplication, which will try to keep the entire Deduplication Table (DDT) in memory. But for most workloads, it doesn't make sense to enable that feature anyways.
That + full-disk encryption is why I went with BTRFS inside LUKS for my NAS.
They recommend 1GB RAM per 1TB storage for ZFS. Maybe they mean redundant storage, so even 2x16TB should use 16GB RAM? But it's painful enough building a NAS server when HDD prices have gone up so much lately.
The total price tag already feels like you're about to build another gaming PC rather than just a place to back up your machines and serve some videos. -_-
That said, you sure need to be educated on BTRFS to use it in fail scenarios like degraded mode. If ZFS has a better UX around that, maybe it's a better choice for most people.
1GB RAM per 1TB storage is really only required if you enable deduplication, which rarely makes sense.
Otherwise, the only benefit more RAM gets you is better performance. But it's not like ZFS performs terribly with little RAM. It's just going to more closely reflect raw disk speed, similar to other filesystems that don't do much caching.
I've run ZFS on almost all my machines for years, some with only 512MiB of RAM. It's always been rock-solid. Is more RAM better? Sure. But it's absolutely not required. Don't choose a different file system just because you think it'll perform better with little RAM. It probably won't, except under very extreme circumstances.
32gb for me because half of that is given to the development VM