This will be a pretty short post about my thought on this certification. I got the certification just because it was free and I wanted to see if it was something I'd suggest for others.
Per usual this isn't something I'll classify as needed. If you are hiring developers or you see that your app installs are stalling then I highly recommend you take the course to prepare for this certification. There is no real world value to this cert which is what I expected because mobile app jobs are mostly based of proof of experience. That being said I think the course material will really help those looking to make apps understand the play console which is invaluable even if your not writing the code.
I learned a few things myself that I want to implement like maybe doing custom listings for Trade Book or adding languages in Medical Notes. I also think that after taking the classes and taking the test I understand why I should make certain choices a bit more. The most eye opening things for me were around understanding video promo videos and the difference between short and long descriptions. I plan on running a few experiments as I update my apps to see how things go. I'll try to document the journey as well.
TLDR: The certification itself won't help you get anywhere but the suggested course could help you understand the console better and improve conversions.