If someone was getting into Product Management today, what resources would you point them towards, so that they have a toolkit and understand the job? 

ie The Lean Startup. Jobs to Be Done.

In no particular order:

-Customer interviews. Atlassian has a good primer https://www.atlassian.com/team-playbook/plays/customer-interview
-Invest time in understanding engineer counterparts communication styles and preferred ways to organize work (assuming tech PM). Not a resource per se but, in my experience, one of the highest leverage uses of time when starting as a PM.
-Continuous Discovery. I like product talk's guide https://www.producttalk.org/2021/08/product-discovery/
-Wardley maps for all products under management
https://learnwardleymapping.com/
-Agile development and user stories (even if these aren't used on tickets for eng, I've found user story writing as a forcing function to reinforce I understand the user persona, what problems they're trying to solve, etc). https://www.atlassian.com/agile/project-management/user-stories
-Jump into vibe coding

a jiraffe on the internet • nf.td/morereese

Awesome. This agile development primer is really what I was looking for.

That Atlassian resource has tons of great info. I referenced it all the time when I was a PM.