At least 300K more troops and a Major production surge in equipment to stop Russian invasion of Europe...

The numbers don't tell everything.
For instance, Finland has a population of only 5.5 million and a military force of 24,000. However, in wartime, it can mobilize 280,000 soldiers, and have a supply of 900,000 reservists that are military trained. Because in Finland, military service for men is compulsory. Yes, this isn't a full-time professional army, but don't underestimate how many could mobilize across Europe. As said, if push comes to shove, Europe would push, in a similar fashion to what Ukraine has done the last few years. It wouldn't be pleasant for anyone.