See https://www.longsteve.com/fixmybugs/vt220-terminal-meet-raspberry-pi/Connect for one person's write-up on how to connect a serial terminal to a Raspberry Pi, either through a USB to RS-232 adapter or to a Raspberry Pi's serial pins via a TTL to RS-232 adapter. If you connect to a Pi's built in serial port pins note that it's a 2-wire interface (ground, transmit, receive) with no control signals supported so if you run at a high baud rate the terminal not be able to keep up and could drop some characters from the display, but really who can read text at even 9600bps (approx. 960 characters a second)? Also may sure if connecting to the Pi's serial port pins that you choose a TTL to RS-232 adapter that uses 3.3V signal levels for transmit and receive.
With a serial terminal connected to a raspberry Pi or other *nix system, you can telnet from the Pi to other devices on your LAN. And see https://www.isticktoit.net/?p=1728 for some other ideas of things you can do with a serial terminal connected to a *nix system like a Raspberry Pi. There are plenty of other articles out there on the web on how to do this kind of thing.
