Given what Ukraine is managing to get past Russian air defences, do you think Putin is going to nuke Europe and risk French nukes hitting Moscow and Petrograd?
That's not how this works; Russia comes at more powerful opponents sideways, with incrementalism, division, and hybrid warfare. They try to get pro-Russian candidates elected so that they can veto collective action. They have "accidents", such as missiles flying into your airspace, to probe how you'll react, and if the reaction is insufficient, probing ops can go further, or become normalized so that you get used to it and then don't freak out when they go a bit further the next time. They famously support "pro-Russian rebels" (quotation marks definitely demanded) in countries to try to break off chunks, and encourage secession movements. Russia prefers to work piecemeal, tearing apart countries by chunks, and only launching large-scale invasions when they think (rightly or wrongly) that they can get away with it.
Do you honestly think that France would fire nukes at Moscow - and thus face nukes raining down on Paris - if quote-unquote "Russian Separatists" with suspiciously good arms and military training took a chunk of one of the Baltics or Poland? Of course they won't, and Russia knows that. And then, "Oh, we're just sending aid to the oppressed people in the separatist regions!" "Oh, the separatist regions have requested help from us, we're sending advisors!" "Oh no, the separatist regions were "attacked" by their oppressive government, we must launch a counterattack in response!"
This is hybrid warfare. Nobody fires nukes in response to hybrid warfare. Meanwhile, Russia gets incrementally more powerful with each region it captures. A couple decades ago Chechens were bloodying the Russian army. Now they're dying on behalf of the Russian army in Ukraine. Everywhere they take represents human, industrial, and mineral resources. People are constantly propagandized to and kept in a state of poverty from which only service to the Russian state can rescue them.