Current state of the #MailStation homebrew software: a singleline text field for user input, and a much larger multiline text field for program output. So we now have a terminal-like interface we can use as a basis for writing command-line software.
Cidco MailStation (black keyboard with built-in grayscale LCD screen). The top of the screen reads "Programs can display output...". A rectangular field near the bottom of the screen reads "...and also accept input", with a vertical bar cursor.
I have now written a #z80 machine code monitor for the #MailStation. The command set is very influenced by WozMon, but unlike #Woz I haven't managed to fit it in 256 bytes (yet...)
So now, in the strictest sense of the word, I have a #repl on this thing!
(While there was already a built-in hex editor, it was not suited to interactive use. A reboot was necessary to test changes, and it was restricted to writing dataflash, which has a limited number of write cycles.)