Between bash aliases and API

Is there a cli program to create custom APIs of sorts very rapidly?

This would be something where you quickly create single command prefixes with a space after the prefix, and then sub-commands you place in that "domain" you created.

Now, I understand a very close second might simply be a self-written program that can do this, or just writing bash scripts that do it, which is not that complicated. But just wondering if there is something out there specifically for this that's just a bit more capable than bash aliases. (or if aliases can do it and I just don't know it.)

e.g.

I imagine a cli program that works similar to the following steps:

1. run alias entry program
2. enter a label/domain/prefix (creates it if it is not already created.)
3. enter new alias name to add to that domain.
4. enter command to be used for that alias

So, you have mini APIs that you can build over time. Subsequently, a domain can be specified as a prefix, or you can enter it as an environment.

The program is configured to place the commands in a config automatically

You could list all commands under a specific domain, or list all domains, and so on.