I am a technical product manager, used to be a software engineer, and made the switch a couple years ago now - wrote a bit about it here
https://bobbiechen.com/blog/2021/11/28/moving-to-product-man... , but here's some more notes:
1. Actions - my manager also offered that I could spend more time doing something more product-oriented in a transition period. My team owned an internal tool for managing firewalls with many long-standing UX complaints, so I took the opportunity to redesign it - collecting and summarizing the past complaints, putting together a new design, and testing it with users. Then I implemented it myself, shipped it, collected relevant metrics, and made some tweaks for later feedback. This was pretty successful, I liked it, and I took the chance to switch to be a PM full-time when a new role opened on a different team in the department.
2. Resources - Inspired (Marty Cagan), and Escaping the Build Trap (Melissa Perri) are good starting points. My company also sent me to Pragmatic Institute training, which didn't cover new ground but did provide lots of template docs if that's your style.
3. A note of advice: going from dev to PM gives you certain strengths. You're naturally going to have a stronger opinion on developer-focused products, APIs, SDKs, etc., and better ideas of what's easy/hard/impossible to implement technically. This is good, but it's not a substitute for talking to your customers/prospects and engineering team. It's really important to actually talk to people, whether by video meetings or chat/email/doc comments.
Also happy to chat in more detail, I'm reachable by the form on the homepage of my website.