Auto-Populating Category Topic Templates with Usernames

We use Category Topic Templates (Topic templates for categories and other alternatives) against a Space Booking category, where the user needs to enter their username into the Template - currently this is done manually.

Is it possible to auto populate a Topic Template with details like the poster’s username?

Discourse Templates has the feature, but is unsuitable for our use case because we want the template to appear automatically when the category is selected

Also - is it possible to use Topic Templates to auto-populate the topic title?