Off the top of my head in 1/56th scale there is:
Perry Miniatures - a few support vehicles / artillery pieces besides carrying the Blitzkrieg range
Heer 46 - do Italian artillery/ whif tank
Anyscale Models - do Italian armoured trucks, FIAT 3000
Mad Bob Miniatures - a few tanks
Rubicon Models - have an upcomming plastic Italian line (delayed by the Pandemic)
Great Escape Games - do field guns, which are useful if you're looking to make gun trucks
If you're counting 3D prints then Paint and Glue Miniatures do loads of things - they're just not all listed on their site currently (email the owner and he and check his files if something isn't).