I created a little app to scan barcodes connected to a sharepoint list with generated barecodes. The scanner works well, but I am unable to filter my gallery with the code written in a TextInput. I tried multiple formulas using Filter or Search but I reached my limitations. The number of the barcode is written by the scanner, but the filter's function won't work.
I think you need to filter using columns in SharePoint which is the data source of the gallery and the textinput is not part of this data source. This is the reason why gallery won't filter using your textinput control.