For me, my high bar that I have yet to beat, was the time I pivoted the running OS (ubuntu) into RAM over SSH so I could unmount and image the boot drive without rebooting and loading a live USB (Which would have required a ticket with my provider to enable IPMI)
Migrated a server to a new drive by copying all the files with rsync and chrooting into it. Nothing too impressive from a linux standpoint, but I had no idea that was possible until I tried it.
I used to do this to migrate user profiles on Macs at my previous employer. I’d ssh in and copy everything across the network and then have the user log in on the other computer like magic. Network copy is a beautiful thing.