Are we allowed to ask here if a question might be off-topic?

Question

Or to get input on a question?

Answer 1

Yes. That is one of the main purposes of meta.

If you look at the meta sites of other SE stacks you will find several instances of "Is this on topic". It is part of the process of creating the scope of the site - look here

For example here on English Language & Usage or Mythology or Board Games.

This is especially true early in the site's life because the community is still defining what is, or is not, on-topic. Such questions should be asked.