Apple doesn't make any hard drive enclosures, but your iMac uses a standard 3.5" SATA hard drive, just like you'd find in any regular PC.
Here's a link (Amazon US) to a decent drive enclosure that will work with the hard drive in your iMac. It comes with the power supply that's needed since you have a desktop hard drive. If you don't want a full enclosure you could get something like this that just connects to the SATA power and data ports on the drive.
Connecting the drive to a Windows PC: do you know what version of macOS your iMac was running? Unless it was upgraded with an SSD at some point it should still have a mechanical hard drive (SSDs were offered from the factory, but they were quite expensive, so most came with mechanical drives), and if it has the mechanical drive it'll be formatted as Mac OS Extended (Journaled).
Windows cannot natively read this format, but you should be able to use something like HFS Explorer or another similar program to access the drive on Windows.
Hello there, thank you. Is there any way of diagnosing beyond what is outlined in #3?
I run a Pi 4 4GB that boots from an old Samsung 840 EVO SSD via SATA to USB adapter (no SD card), connects ethernet to my router, and plugs into a surge protector strip with the official RPI 15W USB-C power supply. So far I have:
Checked voltage across TP1 on normal load (2.53 on cpu / 54 C / 66% RAM utilization) and then running stress-ng on high load (4.00+ on CPU / 75 C) and both registered 5.1 V. Pi working fine.
Replaced my SATA to USB adapter to this UGREEN one. This adapter has an optional power supply, which I'm using and have plugged in to the power strip.
After replacing the adapter yesterday, the PI was operational for at least 15 hours, but sometime between the night and this morning it became unresponsive -- endpoints unavailable; SSH usually refuses connection but this time it just was unresponsive. Unplugged and replugged it in, back to working again.
Next thing I'll try is connecting directly to an outlet instead of the power strip. If that doesn't work, I guess I'll try replacing the drive, but the failure is still a black box for me (and typically takes days between each test). Any thoughts or suggestions?
You can buy something like https://www.amazon.com/gp/product/B00MYU0EAU/ for each drive and get something like https://www.etsy.com/listing/1085108593/8-bay-hard-drive-rack-holder-cage-case to hold them