Hi @burningchrome - My experience is that my Obsidian notes, indexed to DevonThink on the desktop, do appear within DTTG.
However I never actually use that…partially because it seems as though it would be very easy to create a situation where notes were edited in both places given how iCloud sync can be laggy with Devon…
…but mostly because editing the Obsidian documents folder directly via 1Writer or iA Writer is just a way nicer experience - better writing environment and quicker sync.
My attitude is that changes made on iOS will float back over to DevonThink on the desk eventually, but if these are notes I’m working with in Obsidian primarily anyway that is the priority.
I don’t think anyone loves the current iOS situation but 1Writer and iA Writer are both pretty capable…with 1Writer I’ve been able to add a “jump to header” macro I found, which is a nice equivalent to the Outline plugin and makes it easy to move around in longer documents.