Android runs on a unix kernel.

I personally think an open source android rom is a good middle ground between running a full linux OS and google’s Android.

I don’t know what roms are good right now though.

I would probably go for a fairphone and install the non google rom: https://support.fairphone.com/hc/en-us/articles/9979154556817-Google-free-Android

Or check if your current phone is supported by any open source Rom.

In any case you will most likely have a lot less apps since you would have only access to non google play services apps. There is a fairly decent choice of apps on F-Droid but your experience will remain limited.

This is an article from 2020 and I’m fairly sure it didn’t happen.

Out of curiosity, you say an overwhelming conventional force. Does that mean the NATO plan explicitly says it should be conventional?

I always imagined that if a country nukes another they would immediately be nuked themselves. Because if a country is using their nuclear arsenal, it’s probably a bit late to moves armies around.