Ask HN: Guide for a Postgres Newbie, Coming from DynamoDB

I'm a long time user of DynamoDB for various reasons. I never had to chance to use Postgres for real world. Now, have a new startup and my data model and access patterns do not seem feasible for Dynamo or other document/nosql DBs at all. I'll be probably using Aurora. Another reason is I want to learn Postgres, because its mostly a safer choice. I'm a Spring Boot/Kotlin person because it is currently the fastest way to production for my startup and idea. What guides, good resources can anyone recommend for someone in my position? Everyone here on HN recommends "Postgres is good enough for you, don't look for adventure" in many posts/comments, so thought that would be a good place to ask.