In a desktop linux terminal, Ctrl-^ or Ctrl-~ work for me. In a tty, I need to press Ctrl-V before them.

Yeah Linux still works exactly this way. The modern WIN32 API even works that way too. When you ReadConsoleInput() it gives you teletypewriter style keyboard codes. When I wrote a termios driver for Cosmopolitan to have a Linux-style shell in CMD it really didn't take much to translate them into the Linux style. We're all still using glorified teletypes at the end of the day. It will always be the substrate of our world. One system built upon another older system.

I think it's worth mentioning that Ctrl-A is ascii 1, Ctrl-B ascii 2, etc, as it is in Unix today.

you can still type them -- alt + 030(for instance) on the keypad will insert that RS character. In Windows at least -- not sure about the other OS.

On Linux terminals entering control characters is done with the control key, Ctrl-G for example, but they will often be intercepted by the program that is running.

Bash will insert the control character (rather than interpret it) if you prefix it with Ctrl-V.