The panzerfaust was the ubiquitous AT weapons of volksgrenadiers since easy to use and spammable. STG44 was also a common weapon in volks units, though with shortages, since they were trying to make up for lack of manpower via automatic weapons. I do wish MP40s were somehow connected to volks.
I think the MP40 wouldn't be entirely without cause, since there probably wasn't enough StG 44s to achieve full numbers in all cases so it'd stand to reason for some of them to get the doubly-produced MP 40s instead.