Thanks for your reply.
Sure. Implement a driver for that redirection which behaves as an int14h handler and place the address of its entry point at address 0000:0080. (14h*4)
The method works with any BIOS.
I would like it to work with any OS that uses INT 14H (regardless of how many of those exist), rather than any BIOS.
For now I am happy if it only works with SeaBIOS, and I will simply buy a PC that allows me to flash SeaBIOS onto it.
Other manufacturers can do other things with INT 14H, redirecting it to some other device, such as HAM radio.
If suitable for your hardware you could do all of it in an option ROM.
I'm not familiar with this terminology. Is this something that goes into SeaBIOS? I'm expecting it to be something that is set up (and even configured by the end user in the BIOS) before my OS is even loaded.