I do think that if Ivan is crazy enough to invade, he will get thoroughly mauled by the Ukrainian forces.
Last time Russia invaded (2014) they were able to get a foothold in Donetsk and Crimea because everybody said "There's no way that Russia will invade" and the Russians wrongfooted everyone by getting their supporters in Ukraine to stage an uprising first... then they sent in their own forces (whilst denying they were doing it) to occupy ground whilst everyone else was too busy trying to sort out the internal conflicts.
However, Ukraine has increased it's ground forces and added extra bits of kit that could tip the balance... such as modern anti-tank missiles from the US and drones from Turkey (drones that have just swung a conflict between two of the "stans").
On top of that, various countries are providing intelligence (daily Rivet Joint flights on the borders... Public knowledge) and we ourselves have provided Landrovers, Patrol Vessels, First Aid training and equipment, communications equipment and various training exercises.
In addition, Russia no longer have surprise. All of the political denials by Putin and Russia in general are being ignored and everyone is telling Putin that we can see what he's doing... the same thing the Russians did in Georgia, Chechnya and previously in Ukraine.
I think that if it does get messy and the Uki's manage to hold the Russians off, they'll push to kick the Russians out of Crimea and the Donbass and reinstate the pre 2014 borders.
ATB from HTB
ATB from HTB