Re Finland.
WWI started when multiple defence agreements were triggered in a chain reaction.
Thus Finland being in a mutual defence pact with the EU creates the following situation.
Poland, Latvia and Lithuania are automatically is at war with Russia if Russia invades Finland. If Russia then attacks any of these, it effectively triggers the NATO defensive pact.
So a casade effect is likely anyway.
The problem would be something like a nuke strike on Finland. Thats going to obligate the French. But not the Americans and British immediately.
Theres also a command and control element here and a share intel issue though and that's probably more of a problem.
At this i note yesterday's meeting between the cia director and the finnish president.
Its suggestive of at least an informal bilateral arrangement and making a point of good relations publicly.
So NATO can't / wont put a load of preemptive troops in Finland if Russia was to build up troops on the border.
I note the following. The Finnish have landmined the border very heavily. They are one of the very countries in the world who refuse to sign up to treaties to get rid of them, despite significant international pressure to do so. History isn't forgotten by those who endure it and thats a very good example.
So yeah, Russian is perhaps unlikely to launch a land attack on Finland for that reason alone. And an air or missile attack can be responsed to by allies very quickly anyway. Including via Nato.
Finland also has compulsory national service so everyone has some experience of what to do if needed.
I doubt Finland is much more concerned than any NATO member for this reason.
There is just a practical coordination element to consider if the worst did happen - and the CIA talking to the Finnish President definitely suggests some talk of this is going on.
Basically EU does not equal NATO, but an attack on the EU almost certainly means the NATO defence pact gets triggered in a domino effect. All those concerned have a reasonable level of understanding of this.