what should I do with this pile of old (wiped) hard drives?

Open em up and get those wonderful lil magnets out to add to your magnet collection

nas, keep them around for backups, sell them online,

donate them to people in need?

Give me those hard drives (just kidding). You can host a big media server using jellyfin since you got a lot of disk space.

Stick them on eBay saying they might have had your old crypto.eallet.on them but they got corrupted and can't workout which

Another NAS!

Data hoarding is fun!

Backups ? Set up a nas for a friend or family member ?

throw them into the ocean

Throw them in the electronics recycling container if you don't need them.

Take them apart. It's fun to play with the little disks inside

give them out, turn them into portable drives with an enclosure or sell them?