Hey …
I have a tutorial about dropdowns and connections: https://www.totallycodable.com/post/dropdown-list-doesn-t-work-as-intended-or-dropdown-is-disabled
Tutorial about conditional filtering (which also shows an example on creating dropdown list via code by removing duplicates): Conditional Filtering for Dropdowns on Wix | Corvid Tutorial - YouTube
And just in case, tutorial for navigating using dropdowns (which uses examples of query and filtering): Use Dropdowns to Navigate via Dataset Filter or Query (URL text or Dynamic Page URL link field) - Tutorials - Totally Codable