I think it is difficult to say, by late 17 into 18 many, many units had Assault troops.
It remonds me of a memoire of a SAS guy who fought in the Falklands. They were told they were up against an Argentinain Special Forces unit. When they captured them they found them to be a bunch of pimply conscripts. They were "special forces" simply due to the fact that they had been badged and told "now you are special forces".
As the war progressed and Sandbags became a symbol for the "elite" it seems more and more units began to create "assault troops". Some would have been better than others, and a few may have become "assault troops" because they were the youngest, had had 2 days training from a guy who had been on an assualt course and then got two sandbags to hang around their neck.
So yes, the Gewehr 88 guys could technically be "Asaault troops" for a landsturm battalion, or any number of units where there were not enough 98 carbines to go around.
Pits there is not a unit stamp on the back to clear up the mystery.