First of all thanks to organizers for such a great event and especially for the ability to free and almost instantly to access session recordings.
Here are some my takeaways to deep dive further.
The most interesting theme for me was attention to security, this topic was important and is becoming more and more important nowadays. So there are several related sessions to check out:
There was also huge attention to data streaming and related architectures
One more important point of software development is documentation and there was also attention to it: