I accidentally found out that mpv can play videos from the TTY, meaning I don’t have to log in to a graphical session. It even has a scaled OSD, unlike anything I’ve seen in a terminal UI.
Obviously there are plenty of terminal applications that work in a TTY, (edit) intext-mode or using ncurses (/edit), but are there any others like mpv that aren’t strictly terminal apps but don’t require a display server (maybe because they do the job themselves)?
You could include pass. It is a password manager that is primarily terminal-based, but because it uses standard GPG encrypted files to do so, they are viewable in your file browser and there are graphical extensions for your web browser.
It also uses Git so you can sync it to a remote repository, and Git can be seen as another application that works in a similar manner. It is terminal-based, but there are graphical front ends like gitg.