Norko soldiers are underfed, under trained, and physically incapable of prolonged combat.
Their grunts mostly work in the fields, and while better fed than civilians, they are still hungry most of the time. Indeed, North Korean's have been getting smaller and weaker, with more health issues, due to systemic multi-generational malnourishment. The ones seen at Panmunjom are an elite largely chosen for their ferocity and better stature.
Of course, their Officers live a more privileged life, especially the higher up the chain you go, and have little real contact with their commands. Actually going to war would be a major hardship and essentially a death/exile warrant since they could never be allowed back.
Recall the Russians have already spoken of using Norko "Volunteers" to rebuild the conquered territories and damaged portions of the two faux Republics. Decode, any such numbers of "Volunteers" would come down to doing Coolie labor that their White Russian masters think beneath them.
Consider the logistics of moving 100,000 Norkos to Ukraine. There are not enough Russian transport/passenger planes in flyable condition to carry them all, much less if they bring their own weapons, which would kinda be necessary.
The Russians are running out of their own equipment, not least tanks and field artillery/ammunition, and training 100,000 non-Russian speaking troops to use weapons new to them would be a nightmare. Ivan's not even training his own, so an army of foreigners would have to come "ready to play."
Moving those "Volunteers" via the Trans-Siberian Railway (it's still only a single track) would take weeks, if not months. Just marching them to Vladivostok to get aboard would be a major undertaking.
And then there's the kibosh on the whole deal: Un would never let any of his people see the REAL world, not matter how effed up Ukraine is just now. Seeing hundreds of thousands of homes (even if destroyed) with indoor plumbing, paved roads, telephones, televisions, and crops still growing in endless profusion would all poison their minds (after first shredding them) with the reality that their home is not the Socialist Paradise.
If Un actually sent them, he could not ever let them back. They would end up a permanent Coolie class wherever the survivors were settled, likely in Siberia where no White Russian would have to deal with them.
In the end, if this happened, it would be one of the cruelest acts of inhumanity in modern history. Which, unfortunately, would be perfectly in keeping with the Norko world view.
All that said, on the whole, I think this is also a publicity stunt and nothing will come of it.
Unfortunately, I'm ready to be disappointed, again.
TVAG