To model a DD M4 Sherman with screen deployed would only be for display since the vehicle would be mostly beneath the waves. However there are many photos of DD Shermans still carrying their screens after D-Day operating miles from any beach. They were also used in southern France landings and some river crossings.
So a kit that would have collapsed screens that could be fitted to an M4 Sherman with the propellers as attachments to the hull is possible.
As for Berg Panzers and common parts, at this scale a jack is a jack, would there be that much noticeable difference between a Pz IV or Panther one? Tank bars, wrenches, tool boxes, jack handles to me appear to be pretty much the same.
The spade could be made large and able to be assembled smaller for the 38t BP or in piece components.
Well, maybe scratch that. I looked at the tamiya Famo accessory kit and the Jenz book at the Berg Panther spade and they are vastly different.
A Panther accessory kit could include the mantel to make a Panzerbeobachtungswagen Panther, the spade and parts to make a Berg Panther, a FlakPanzer V Coelion , 2cm Vierling Flak Panzer or other variants.
Then along the Flak Panzer vein a kit to make the Panzer Kampfwagen IV Flak Panzer variants: The Mobelwagen, the Wirbelwind, the Ostwind and the Flak Panzer IV Kugelblitz.