No gpio but old centrino laptops make excellent low power servers. My primary server was a first gen centrino from 2011 up until recently and I think it only used 12w idle after putting a SSD in there. Had it's own UPS built in.
What kind of place do you go to to find these things? Sometimes I get really lucky (see my post history about my wonderful new printer), but if I could increase my odds that would be cool.
Back when I lived in a (quite nice) apartment building I was constantly surprised at the things people threw out. Perfectly good furniture but also stuff like perfectly functional printers, artwork, computer cases...
If you go near college housing there's usually a given day of the year (either moving day or an official cleanup day) when tons of people put out stuff they don't want to bother with keeping/moving. It's Hippie Christmas baby!
I think 5W probably can't be achieved, maybe with chromebook-like hardware, but I guess GPIO could be solved with a USB accessory
in my opinion the bigger problem is the fire hazard of an unsupervised charger. I have seen enough that runs super hot, and even if it doesn't, I just can't trust them.
I'm in an apartment building, so I just browse the one here whenever I take the trash out. I don't think anyone has noticed, or they've elected to mind their own business if they have.
There's so much stuff that could still be used that it honestly isn't funny, and that's just in my own bin. How much more is being wasted across the country? But at least it's in the recycling and not the trash, so that's something, I guess.
About to be? The bottom has been falling out for desktops and laptops on processors not on Microsoft's supported list for the last year or more. I've seen roughly the same system go from ~$200+ down to under $100 on the last year based on eBay pricing alone