How to prepare for embedded role as newgrad?

Hello, I'm starting a NG position at a large tech company. I initially was supposed to go into an entirely different world/org but have recently been moved to a cloud/virtualization/embedded/OS team (AWS EC2). The only low-level course I did in college was computer architecture. I didn't do compilers or OS. My manager reached out recommending I "brush up on topics of Systems architecture , Embedded and OS level".

I'm just wondering if anyone has recommendations on youtube series/udemy course/personal project or anything else they'd recommend for setting myself up for success?