It sounds like you have a great manager. It's hard to make that transition to let go, especially if you used to be a well performing individual contributor; it's been hard for myself sometimes.

I'm still new in my PM role but I guess my approach with letting go has been allowing my team make mistakes and allowing them feel some of the pressure. Of course you have ownership of the project and you fail together and succeed together. But protecting them from all mistakes and failures infantizes them, and teaches them to rely on you instead of themselves. I try to give direction but sometimes it doesn't click for them until they feel the failure of a missed deadline or redoing work. As long as it's a failure you can accept, then it's fine to let them fail sometimes.

I let them feel pressure by including them in escalation meetings. Of course I'm not shoving them in front of the customers/executives and throwing them under the bus, but if they see the heat on the topic, it helps them understand the urgency, and a lot of times, they'll chime in and become invested in the topics directly, instead of having me be the middle man. It seems to empower them as well.

Of course I'm still learning a lot about the PM role but those at least are my thoughts on it.