Most people will be too busy with their laptops, tablets, and phones to pay any attention to whatever ads they put on those screens.
cmnybo
Just make sure the file doesn't have a double extension. That can trick people into running a .exe when the file extension is hidden. That's really only a problem on windows though.
I used to run a GUI on a Raspberry Pi B+ and it was doable, but that was a decade ago and many programs have gotten a lot more bloated since then. Of course if you are just running your own software, you can optimize it to run with very little RAM.
It depends on what you are doing. I've got single board computers running happily with 512MB of RAM. I certainly wouldn't want to try and run a GUI on them though.
There is not much AV1 content because there are not many platforms streaming AV1 yet. Transcoding a lossy format like H.264 or VP9 to AV1 will reduce the quality.
It's getting harder to find routers that will run open source firmware. The best option is to run OPNsense or pfSense on a low power x86 machine and use separate APs for WiFi.
Have you tried running a speed test with and without the VPN while nothing else is using any bandwidth? See how that compares with the torrent speed.
If the machine has 4GB of RAM, then MATE, XFCE, LXDE, and LXQT will work well. I've used all of them on older computers. The distro doesn't really matter. If it has 8GB of RAM or more, it will run any DE you want to use.
If the machine has less than 4GB of RAM and can't be upgraded, it's not going to be very useful. Sure, you can put a lightweight window manager on them, but they are not going to run a web browser well. They could still be used for teaching students how to install Linux though.
There are very lightweight media players available that will run on anything with enough CPU power to decode whatever codec you are playing. It's modern web browsers that will be an issue with less than 4GB of RAM. There are lighter web browsers, but they usually don't support javascript or have very limited support for it.
A lot of media players have a compressor if you are watching ripped movies on an HTPC.
It depends on the version. I ran windows 98 on 64MB, then I upgraded and ran windows XP on 1GB for quite a while before switching to Linux.
It certainly wouldn't be OK for anyone that actually wants to use the in flight entertainment. I watch whatever TV shows and movies that I downloaded ad free and never turn on the seat back screens.