Would you please explain a bit for the SharePoint list, specially for the Categories field?
To get the Choice Field Value, you could take use of:
DataCardValue.Selected.Value
If the Categories field is a lookup type field, then the lookup() function should be written as below:
Lookup(SharePointList, CategoryField.Value=DataCardValue.Selected.Value, acronymns)
And if the Categories field is a string field, the nteh formula should be changed into:
Lookup(SharePointList, CategoryField=DataCardValue.Selected.Value, acronymns)
Regards,
Michael