Drop down or search box with more source options

I have a use case where a drop down or search box (prefer search box) has a source of a list of things. I currently set this list of things on page load (i.e. projects I can view and projects I can edit), so I don’t continually do a search for. The issue is that neither drop down or search box gives me an option to set the source as anything other than a basic query. It also does not support merge with or anything that would allow me to get the data I need.

any suggestions would be appreciated.