I downloaded Obsidian and it looks really nice. I use markdown already to make notes on my side project, but in my brain my thoughts are more diffuse as it's an MVP stage thing with so many ways to extend, so many things to think about. I think this would, at firs glance, help me alot.
One small thing I'd recommend would be when you first open it, could it create a default folder like (on Windows for example) Documents\Obsidian. And pre fill that as the folder (and I can change if I like). Then when I first use it there is less friction.
The other thing is to UX test that first screen where you are made to choose between new document and reading docs. I felt that made me think too much, and it might be the wording. I'd sort of prefer something like:
New User? Do you want to read help on getting started? Yes/No.
However I might not be typical, so watch over some shoulders as people first use the app and ask them what they are thinking.
Good luck!