That is a problem of Penal that need no side tech and not conscripts, side tech is good from a design point of view. It the Penal that need to looked at and not conscripts especially if OKW start get toned down.
You
could lock Penal troops's stuff behind the sidetech, but then the sidetechs would become automatic purchases.
And if the sidetechs are automatic purchases, there's not really any point in having them. Just factor them into the teching cost instead.
USF and UKF pulled off sidetech acceptably. Soviet's sidetech has been a train wreck from the start.