I think this is a good option. OKW engineers have four STG-44, British get 5 people but can buy any weapon. Wehrmacht engineer can get the 5th person with STG-44 as a sergeant. Soviet? Maybe 5 people and 2-3 PPSh-41 or SVT-40. Since there is no possibility of adding new models, I have no other options. PPS-43 would be appropriate for the Soviets.
Conscripts have mostly mosins and hopefully by default upgrade option SVT. It would better for the engineer to have PPSH similar to the style Wehr Pios have with close range DPS or focus.
The fact Brits engineers can become more powerful seems clearly unfair. I think every other faction deserves more out of their default engineer/pio units.