I wouldn't say that screens themselves damage attention spans or anything, but when the screen is the tool to deliver the lowest consumable content imaginable, cutting out the screens is the way to go.
This recommendation is understandable, but as with anything moderation is key. Not just in terms of how much screen time you allow, but the type of content they interact with.
I've got two kids, the amount of time they get consuming content is limited, the content they have access to is only from my media server (so very curated), and occasional extras like crafting/drawing/etc when we are sitting next to them. And even that I'm moving to the media server due to the ads, which are impossible to really curate and can be very, very odd...
The physical presence of a screen being on is not an issue. Using it as a replacement for parenting is an issue. Especially under 2.
I just wish it wasn't so much effort to manage content that other parents could do it more easily.
We also have a media server, and I too wish it were easier to set up so more parents could have more control over the content viewed. As it is, I'm thinking to upgrade our machine so it can handle multiple streams both locally and from other houses.
The other parents we interact with like the concept of limited curation, but they lack the technical experience to get it set up and so they rely on Netflix, Prime, and Disney+. Maybe I'll get around to it this winter haha.
That's what I do, nieces and nephews. They are a bit older than my kids, and their parents are not tech savvy.
I basically have a kids library for anything under PG, and I grab common sense media ratings for a decent estimate on appropriate age, and let them go from there. Then I use tags for what we find appropriate for our kids.
Some of them still use other things I wouldn't go near (YouTube kids, ffs that place is wild and weird), but that's their decision not mine.
FWIW I run mine off an 8th gen Intel, igpu for transcoding (though mostly I don't need to transcoded), on a little lenovo tiny workstation I picked up on the cheap. Storage is on my NAS.
We have a Nvidia Shield so transcoding isn't needed for us either. Our server is on an old NUC with a fifth generation i3. Started overheating a year ago so I removed it from its case. It's running Windows though so now that the little one is back in school I might upgrade it to Mint and see if I can prolong its life.
Regarding YouTube, we have Smartube on the Shield, and have it configured to open to the playlists page, with our son having his own profile. This lets us set up playlists for him to watch that don't include any attention whoring videos and are (at least in part) vetted by us beforehand. Lately I've been considering adding the YouTube content to our server. Smartube is pretty tweakable though, I like it.
With no server-side transcoding, yeah the nuc is plenty, but I also run my media server (JF containers, to be specific) on Debian.
If you do end up needing transcoding, the newer Intel stuff is great. I'm considering arc actually for other reasons, but ideally anything skylake (for HEVC) or Kaby Lake (hevc 10 bit) on up is a rock solid choice, no external GPU needed.