Drive a custom form field dropdown / multi-select options from a designated file

We have a field which contains multiple products that we need the end user to select one of. However the list of products changes quite frequently and we don't want to have to reconfigure all the product fields every time. If they could point to a google sheets file with one column of data to populate the dropdown options, or even a document that could be loaded into WF to maintain its integrity, or a simple SQL db table, that would make the updating of all of these fields (which contain the same data but have to appear multiple times on one form for each phone number the product is associated with), about 1000% easier.