[zzo38computer]

For some things, uxn/varvara will do; it is simple enough that it can run anywhere.

For other things that can run by internet, a subset of telnet and terminal codes might do; however, that is only good for remote services and not for stuff that is more useful to run locally.

For some things, C will do, especially command-line stuff, but also is possible to use SDL, etc.

You do not need so much extra stuff that just makes it slow and takes up more memory and makes it difficult for the user with program working together; for this reason, UNIX pipes are useful because you can put any program together by pipes. (Like, another comment also mention something similar)