I got one of these recently and I'm pretty happy with it. It's a repurposed iPad screen, 2k, 4:3, and put into an aluminum frame. slightly larger than your requirements tho. Got the version with usb-c and mini-hdmi inputs, and is USB powered. https://www.aliexpress.us/item/3256801503431249.html
Yes others beat me to it but they are front ends. Freetube acts very similar to the YouTube browser website on desktop but can use various back end solutions like invidious (I've only been using it for a few days but seems to work this way). I've just left it on the default settings but it accomplishes what I'd like it to do, which is strip out the ads + incorporate sponsorblock.
Newpipe I've been using on android to download videos and music for offline viewing and listening for awhile now, but similar idea.
Decided to start using Freetube on desktop, Newpipe on mobile. It works!
In the vein of multiplayer games with singleplay bot matches like Battlefield 1942 being mentioned, try the standalone mod for for Battlefield 2 called Forgotten Hope 2. Many maps have single player bot support (by launching coop server on your lan). Battlgroup 42 mod for bf1942 has a tons of singleplayer maps too. You can also get bots via third party plugins for the og Day of Defeat (sturmbot or shrikebot) and as mentioned Day of Infamy has built-in bot support. Worth mentioning are the Arma 3 WW2 mods and dlc.