I don't think it's meaningful to even speak of interdiction, Russia is as likely to successfully access ammunition depots in Transnistria as they're in Lviv.

Ukraine on the other hand could crush resistance in Transnistria within a day or two, there's simply nowhere to hide from artillery fire on that narrow stretch of land.

Of course, there's no point in doing that. There's nothing worth capturing in Transnistria, a power plant and a bunch of poorly stored ammunition that's not going to be in usable condition.