Feedback: Please always share pictures, you are building a UI, but not sharing, its much easier and faster for us to see whats wrong, then to be told cause some of us are old :-) and visuals are way easier, both to show us what you want (Mock it up) and if it doesn't work, expression and visuals of what is not working.
Also, I am not sure what you mean you are able to do it in a Form but not here?
You haven't explained the logic of how you decide where to pull the data from, or shared what you did in the form as it would be nearly if not identical. So please share what you did somewhere that worked, and then share what you tried in the Gallery that doesn't.
It's easy enough in the Items property to have a Switch or an If statement to decide where to load data from, but I do not know the names of details relative to the choices etc.
So for instance let's say you had a column called FOO (text column) and if the value is "Me" you want the drop down to load choices from Table 1 not Table 2
In the items for the drop down you would something like this
if(ThisItem.Foo.Text or .Value depending if you use the classic or modern control = "Me", LoadChoicesFromtable1, LoadChoicesfromTable2)
now, since I do not know if these are Table level choices, or global choicies, I just typed in LoadChoicesFromTable1
I am making a super guess leap here as to how to determine what to load, but hopefully it explains how to do what you asked.
If these suggestions help resolve your issue, Please consider Marking the answer as such and also maybe a like.
Thank you!
Sincerely, Michael Gernaey
