I like btop Maybe not really "unknown", but hey for those that don't know about it, check it out!

mlocate

Lightweight sudo alternatives, hard to google too. I know ssu and rdo, please mention others.

paste. I don't think a lot of people know this command, but it can be handy at times

Idk a lot of commands but I think wget for downloading webpages and rsync for syncing devices are pretty awesome

Underrated or not widely known?

I love lazygit and I'm still surprised at how many people are shocked when they see it for the first time. Not exactly a command, but a very handy text UI tool.

For more elementary tools, I can't believe how many people know about ! and ctrl+r who don't also know about fc and edit-and-execute-command.

degit is a tool that will check out a git repo (or a specific branch or commit), but not set it up as a git repo. Basically just downloading a specific commit to a directory.

Bat, a cat alternative.

Lsd, an ls alternative.

Procs, a ps alternative.

Renane, because it's great.

find?

As someone who has to do installs and admin at work a lot I'm constantly dealing with yum/dnf. I cry when I have to work with AIX.