There are some fundamental errors here in how you determine NATO as some potential sovereign force when it isn't. NATO is not a US military arm, it cannot go to war and take everyone else with it. Just for a start NATO has not intervened or entered into any conflict without a UN security resolution.
The fundamental question here is do you side with a country like Ukraine which is facing uncalled aggression or do you side with allowing Russia to unilaterally decide to invade another nation in Europe using force? NATO and world governments have decided to support Ukraine, it has nothing to do with the US.
When you talk of western imperialism you have to consider that empire building doesn't usually involve choice yet the most fundamental aspect of NATO membership is choice. Finland and Sweden are the most recent to unilaterally decide to join but that isn't to buy into US influence but rather because they quite justifiably fear Russian aggression.
Whether you're anti-war or CND is irrelevant, having those views will not prevent bad people from doing bad things as is happening in Ukraine. You cannot tell Putin to stop being naughty in the UN because he will laugh in your face and that has been Russian foreign policy since they themselves started the Ukraine war nearly 10 years ago.
This is why the possession of nuclear weapons is critical, unlike others we have the resources and technology to protect ourselves and others for the right reasons. So why wouldn't we do it? Why should we not work together to protect ourselves and our friends from harm? That's ultimately what NATO is.
I'm not sure of your views but any protest should be aimed at Russia right now and not NATO or the armed forces who right this second now are potentially risking their lives to protect you. If Russia goes any further then it will be them dying for us and our way of life (again).