1. Nuclear forces are a weapon retained for the prospect of national defeat.Russia has a far larger nuclear force than China. Unless China were to send SSBNs west of Suez, China cannot pose a nuclear threat to the UK. Russian incursions in European and UK airspace pose a risk to normal taffic, as well as the veiled message of attack capability. Likewise, increased Russian submarine activity in the Atlantic is to send a message to us.
Russia continues to exports MiGs, SAMs, submarines, naval mines to all sorts of regimes.
You might be interested in this paper about Russia and NATO in Northern Waters:
Fire and Ice: A New Naval Strategy for NATO's Northern Flank
At the risk of sounding paraniod, Dominic Cummings (who spent three years in Russia) seems to have a bee in his bonnet about carriers, and seems to have swallowed the disinformation. Russia is keen is spread rumours that discredit our capabilities.
2. Probing defences is hardly restricted to Russia, as we are deploying a carrier to ferret around chinese newly claimed territorial waters and I'm sure a few RAF types can highlight those low level recce flights into eastern europe that were common back in the day.
3. Exporting arms to regimes you don't like, can be applied to some of the countries we export too.
I am not underestimating the threat of Russia, but trying to put it into context and maybe explain why most UK citizens do not walk the streets in terror of russia. Certainly, if Russia did invade the baltic states then people would accept your and others arguments, but the crimea, donbass and chechyna are not the baltics.