Generally, I'd say that anything in The Sun is probably overinflated tosh (except when they still had their Page 3 Girls, when they at least might not have had much room for tosh on that page).
Like has been said, nuclear shells 'were a thing', during the white-hot heat of "we can easily put nuclear in everything to make it better!" (even Operation Ploughshare stuff, and the Orion launch system) for a Jetsons/Thunderbirds future in peacetime and who-knows-what future in war.
They have, however, moved nuclear-capable forces up against Ukraine (I think the rocketry launchers are the more credible) and ran drills for their Nuclear Forces arm (the whole lot) just a couple of days ago, overseen by Putin, which is either brinksmanship or uncharacteristically bad optics in our eyes (maybe it was a home-facing "look how seriously we all face this threat from The West™" optic) but I don't think it'll actally work as a 'deterent' to the defence of the Ukraine, if that's what they were hoping for.
MAD works if both sides take each other seriously. I don't know about Russia, but I don't think NATO has enough belief that Russia would lob nukes for... 'Greater Crimea', to include Kiev and Lviv? Given that, I can't see how there aren't plenty of conventional long-range weapons already zeroed in on every actual (non-separatist) border-crossing point, or within an aircraft's launch of being so. If anything goes nuclear, it'll be a mis-step from the unknown psychology of Russia, not a Jack D. Ripper/T.J. Kong character. (Worst case scenario: some sort of Valeri Petrofsky doing something underhand to muddy the waters.)
Of course, future-history might prove me wrong, but I predict Cold War-with-border-skirmishes for an indeterminate amount of time, and then what happens next depends upon how Ukraine's population (and president) decide to act upon the reality of it[1], which could go in a number of diverging ways, probably all at once. And I don't think there's enough certainty in there for master-tactician Putin to know it'll go to his advantage, so I don't even know how he thinks he'll 'win' this one.
Making Ukraine (or more) into 'Greater Chernobyl' just doesn't seem like something that'd go through his mind. And even Belarus (its people, if not its leader) might complain about that!
[1] And of course the UN, but what with the Security Council being as it is, this relies upon Russia not being totally frozen out, which relies upon (at least) China not being sympathetic with them. Whether a simultaneous Taiwan scenario is helpful or harmful is a doozy of a question. I can see why some think there's got to be some back-channel coordination between the two. Although I wouldn't put it past either to be prepared to stab the other in the back over the 'plan'.