I wrote about this on Friday in the Java Weekly and given I've been playing with Debug0 over the weekend, I wanted to do a quick weekend email too.
My own use is an internal email app I'm building, after getting a bit overwhelmed by doing support on Gmail :)
Pairing with the agent is, well, certainly powerful but yes, there's definitely a gap in prod, investigating anything that goes wrong. 

The data is all available - extensive logs, stats, debugging, some early observability (still workin on that). But still, putting everything together coherently to pin-point exact what an issue is is manual. 
Was manual. It's pretty crazy to actually get insight so quickly. 
Definitely have a look at their free beta here.