Russia is not going to nuke Ukraine.

Russia is going to annex a huge chunk of Ukraine, which means they'd be nuking their own country. The fallout would also hurt Russian cities.

Russia won the war in Ukraine. They have no need to escalate. If their troops hold their positions for 2 months, Trump will force Ukraine to settle and end the war. The settlement will probably be that Russia gets to keep some of the land their troops occupy, and give some of it back. Also an agreement for no NATO expansion to Ukraine.

This isn't like Israel vs Muslims, where the Muslims are willing to fight to the death to eradicate Israel and will never settle no matter what. There is no settlement, because Hamas has "We take everything you have and genocide you." as their baseline negotiating position. You can't settle when there's nobody to negotiate with. Even if Hamas "surrenders", there still will be non-Hamas terrorist groups who want war with Israel.

Russia will settle if they get to keep a chunk of Ukraine's territory and a promise of no NATO expansion.