Tons already exist. If you’re in the Pacific Northwest then make your donations to https://www.freegeek.org
Deploy code-server and either connect to it with a VPN or open the port needed to connect over the internet.
I’ve used lots of different boards. The Radxa Rock 3c is cheap and has decent performance, but the official OS support is a bit old. The Libre Computer boards are also good and have Armbian support. Libre Computer is releasing a couple more this year too. BananaPi has good options that aren’t expensive, like the BananaPi M5. Friendly Elec has some boards like the NanoPi R2C and R5C that aren’t pricey and have Armbian support. Any one of these boards are fine for a small home lab. Just boot Armbian, install Docker, and add your containers.
Intel Arc A310. They’re $100, support AV1 and powered completely by the PCIe bus. Combine it with Tdarr and you can compress your media library down to half the size easily while still being able to easily stream to any device you have.