My O'Reilly's shop portal does have an input for VIN if I have it, I can even use the license plate number if it has been used for a while. So does AutoZone and NAPA

And yeah, you need to know if 9 or 10 inch drum.

FWIW most of the time a VIN does not answer that question, I have done a couple of Toyota Corolla's recently that you needed to know the country of Mfg, you can determine that from the VIN, but then you had to know how wide the brake shoe was LOL