Used offensively, Russian nukes would ruin your day equally well, no matter where they were launched from. Speaking of which, I have been assured by two Ukraine patriots here that even a single Russian nuke being detonated (purposely or accidentally) near Ukraine would result in the automatic launch of the entire US & NATO nuclear arsenals within 2 minutes. (My guess is they didn't realize they were basically describing the "doomsday device" from Dr. Strangelove - or maybe they did realize it, and were just willing to kill everything & everybody over Ukraine! ;^)
Short range tactical nukes are a different matter. They are an intermediate step in the escalation chain.
Consider a scenario - Russian forces in Belorussia, or using Belorussian airspace, commence bombardment of Polish territory, perhaps to impede Polish support of Ukraine or to damage Polish transport facilities used to move aid to Ukraine. That is an act of war, Belorussia->Ukraine. Poland is inclined to retaliate. If Russian forces then counter-retaliate they could use “tactical” nukes that are at hand in Belorussia.