we live in hell

I am considering expanding my indie pub operation to more than just Amazon, but I don't know other platforms or how good they might be.
I recently heard of Kobo. is Nook still a thing, or did that utterly die?

They do still make Nooks.
I personally got a Kobo Clara reader recently. I like it a lot! It's pretty much the same as a Kindle Paperwhite, for about the same price, but without the closed ecosystem crap Amazon forces on you.
From what I saw it's pretty easy to put your books on Rakuten's (Kobo) store, too.

if that's the case, I'll probably do it. my sales on Amazon have flatlined.