I think it naive to think we can do anything in support of this war without consequence, but I don't think we should be bowed by consequence either.
Additionally we need to be observant and protect what makes this country able to stand up to the likes of Russia - maintain a robust defence capability, the ability to rapidly logistic and back it up and our nuclear deterrent. It is almost certainly Russia will be motivated to try and erode it, include by methods outside of the "rules" as we understand them, and likely have tried in the past - which may include trying to infiltrate the political or social processes to try and rid the country of our nuclear deterrent, etc.
Nuclear even tactical is fairly unlikely, though not impossible, while doing so would put Putin's arse on the line but the potential for tactical escalation, especially if Russia is losing isn't out of the question. Again we shouldn't be cowed by it - bullies like Russia are only encouraged by getting their own way - if they see it works once they will play it again.