Pure Arch isn't going to give you what you want. EndeavourOS is probably a better option. Nice installer, a relatively kind and helpful community on their forums, and you can use the Arch wiki to fill in the gaps.

https://endeavouros.com/

Per their website, everything in the Pixel line apart from the 10a is supported. They will be supported as long as firmware and security patches are available. https://grapheneos.org/faq#supported-devices

Lots of x86 machines are hitting the curb this week because they won't run Windows 10. One of those with a Linux distro installed will do what you want. Follow the directions in Jellyfin's documentation and you should be good. Adding your devices to a Tailscale network is the fastest way to be able to access your content outside of your home network. FireTV has a Jellyfin client and can also be added to Tailscale.