I don't see NATO putting boots on the ground TBF. Bombs, missile strikes, limited activity of special forces, jamming etc, - possible.

It's just too convenient to have Ukraine pay the price in lives. Ukrainian military may be getting more experience than any spectator, even a spectator with access to data from them, but it's less qualified to use that experience for improvement, while NATO militaries are very well qualified.

Also the war going on is in some sense stability, while the war ending would be destabilization in the same sense. They just prefer things moving slowly.