This idiom or expression means:

On the agenda.
Available options.
Available for discussion.

“What’s on the table?” could mean any of the following:

What do you want?
What are you selling?
What are you offering?
What are your conditions?
What options, or choices, do we have?

A. Are we going on a trip or not?
B. I didn’t know that was on the table!!

This idiom or expression means:

On the agenda.
Available options.
The things to talk about or make decisions about.

When someone says “That wasn’t on the menu,” they mean something like “I didn’t know that. I didn’t agree to that.”

When someone says “What’s on the menu,” they mean something like “What are we going to talk about?”