Green Boxes with Computer Components... What are these?

Hey y'all,

I got some green boxes a while back from someone who was really into Etherium. They told me it was part of their old, obsolete setup, and to go ahead and reuse the parts. When I looked inside them, I found what seems to be a RaspberryPi-like mini-computer, and a 6 TB Hard Disk. I hooked it up to my Linux computer, and found a partition with 5 TB of ".plot" files. There's also what looks like a JSON manifest, last dated May 2023.

Green Box with what looks vaguely like the Etherium Logo

What are these Green Boxes?
What is this mini-computer?
What are these .plot files?
Are they normally worth something?
Are they too far out of date?