I have the possibility of getting my hands on a practically unlimited supply of S905X2 Android boxes, they have 2GB of RAM and 8GB eMMC, only 100Mbit LAN but USB-3 as well.
I was joking around with colleagues, what about making an ARM cluster out of them? Use the 100Mbps port as a management port and add a USB3 Gigabit or 2.5G adapter for general traffic. Power the cluster by PoE using PoE to 5v splitters from a smart, management switch with PoE (10W each box?).
Lets say I got 40 boxes with 4 cores, that's 160 cores and 80GB of RAM. It could run Armbian with Kubernetes or something lighter. I personally have no use for it, but it could be a fun proof of concept?
Tell me why I shouldn't do this! Tell me why it won't work and why I'd be wasting my time.
Would it be fun? Probably. Would you learn stuff? Almost certainly yes. Useful as a full time production environment? Nah.
There are worse things to spend your money on. If it all goes tits up, usb network adapters are always useful, especially with the amount of laptops that don't come with network ports these days.