They're small, unobtrusive, silent, low power, useful and fun.
I use a OrangePi Zero with 512MB of RAM [0] as a local DNS, webserver, torrent client and download box. It provides hostnames for devices at home, downloads my LibreOffice and Linux images, allows me to test small static webpages in a package no bigger than a literal match box.
It runs Debian based Armbian and is rock solid after updating it to Debian 11. It makes my life easier and helps me learn working with constrained systems which allows me to be better at my day job.