I’m biased towards TrueNAS scale, because in my experience, it’s been really rock solid, running on bare metal. It also allows you to setup things like Nextcloud/Tailscale/ a lot more, in 1 click from their “app store”. It’s also got all the virtualization bells and whistles. As for ZFS, again, just like everything else, it’s been rock solid and setting up a ZFS pool is pretty much done for you when you install TN Scale.
As for remote access, I’ve always personally done it via a local Wireguard server and can’t really compare it to tailscare or whatever cloudflare does… Because I’ve never used those.
If you need a GPU just for encoding, go on the 2nd hand market and pick up a used Nvidia RTX 2000/3000 card. Intel Arc could also work, but it’s a bit quirky afaik…
150$ is rather ambitious for what you are describing as a custom made low power server. Managing to build something… Anything commercial out of new, hell even refurbished parts that has enough horse power to run anything more than a pihole/DNS server at this price point would be a challenge and a half. If you’re going refurbished/2nd hand, you’re likely gonna spend half of that on just shipping the parts to you.
I believe you are vastly underestimating the price of new low end parts and vastly overestimating the capabilities and availability of old micro servers. I’d say something like this would work at a price range of around 300~400$ (and even that’s ambitious imo).
And even then, that’s a NICHE audience you’d be targeting. It would be people who don’t wanna pay subscriptions, but also don’t wanna be bothered to spend a day or 2 figuring out how to set up a simple linux box on an old computer they have. I’m not saying that audience doesn’t exist, it’s just veeeeery niche.