I remember (much) earlier in this thread advocating for this kind of hard line approach, only to be accused of being a warmonger by various on here. It remains the case though - Putin and Russia only respect strength. Talk of concessions and ceasefires - hell, pretty much any kind of talk - will be seen as weakness.
Next time Lavrov or whoever starts talking about nukes, they should be reminded that other countries also have nukes, and that unlike Russia, their arsenals are probably full maintained and ready to go.
To be fair, Russia's sabre rattling has backfired spectacularly so far. For some reason they keep threatening drastic measures only to have to climb down. The West don't have to mention nukes, publicly test missiles, have ridiculous military parades with full on ICBMs because their capabilities have been proven on actual battlefields in every decade in the modern (and pre-modern tbf) era. There's a reason why China are waiting so long to take Taiwan.
What we do need to do is not give an inch to Russia, something that Germany (and Israel and India and all the other countries who have clear economic reasons to not want to write off existing deals) are clearly doing by trying to stick as closely to the fence as possible. So totally agree with you in that regard.
You have to remember that it's actually really easy for the UK to be balls deep in helping Ukraine as relations with Russia were already non-existent prior to the war. With nothing to lose, beyond the unlikely case of Russia declaring war on the UK, Johnson can do everything he can to help Ukraine militarily and seem like the saviour even though he's done absolutely jack shit to help refugees and alleviate the humanitarian crisis. And to add insult to injury he's actually on a collision course with the whole of the EU and the US over Northern Ireland, something that could have major ramifications in dealing with Russia.
Germany need to buck up and get on board, however it's not a basket of fruit anywhere else once you start scratching beneath the surface.