Exclude certain categories from the Trust Levels

In my understanding badges can meet as many conditions as you are able to write in a SQL query. I’m aware of two topics with examples:

In addition you’d probably need to use a plugin like Discourse Automation or Data Explorer to connect the badge with a resulting action, either automatically or manually.

In that regard you could also skip the badge and just use a recurring SQL query with the Data Explorer to manually reward free membership to the users that match the query.