As part of my Inter-War Period US Army troops I have a movie camera and sound man. B&B Miniatures make them in metal. I got a set and painted them up as US Army troops. The US Army Signal Corps took official photos of military operations since at least WWI. My wargame rules give an increase in morale to troops who are getting their picture taken. My wargame collection involves the US Army from 1637 until the near future. The Army traces their heritage back to the first muster of militia in the Massachusetts Bay Colony. I try and have soldiers for all of that period, particularly for the 20th Century.
Motorcycles from Nitto with head swaps to make US Army troops with the M1917 helmet for use up to 1942. These were used by military police, cavalry and messengers.
A varied group of US Army troops for early WWII including IT Figures, and several other companies. While there are few sets specifically for use in the 1920s to 1942 for the US Army a little searching and a bit of work will turn up some good stuff. You only need to supplement the WWI US Army troops with a few post war weapons, like the Thompson SMG because nearly all the WWI weapons stayed in service post war, apart from the Chauchaut.