The US and NATO could trivially cripple Russia's army in the field. They're entirely unprepared for it and they're going to be operating far from their optimal protection (embedded in Russia where defenses are far greater).
The question is, when would Putin throw the nuclear card on the table.
I'm in favor of the US and NATO (or just the US by itself) immediately attacking Russia's forces inside of Ukraine and destroying the Belarus command structure, including assassinating Lukashenko and pushing a revolution there by any means necessary. Russia is weak militarily outside of their borders and the US could trivially defeat them. It would take most of 2022 for Russia to regroup for a full force projection into Ukraine if they're under attack from the US while doing it, and I doubt they have the manufacturing capabilities right now to sustain (that would take time to enhance).