I’ve heard it said that the horse is man’s best slave.

My main use is as an SSH client. My next most common use is pass (with the password store synchronized via a Syncthing app, outside of termux). And one more I enjoy is pdftk for basic PDF editing operations (e.g. split, merge, remove passwords); that’s been useful at work where it seems like no one’s got PDF editors installed on their computers already.

I host a CalDAV server (specifically Nextcloud’s Calendar app, though plenty of others exist, like Radicale) and all my devices sync with it.