Note: Obsidian is not doing the same thing as DEVONthink To Go so it’s not a 1:1 comparision between the two (or 3, 4,…).
2 - would there be an option to allow DTTG to have a native folder on the mobile device that would sync to the database
You are describing an indexing process here, not something that can be done in Apple’s mobile OS.
3 - Could a daily/weekly/monthly etc document be an option to add as a direct shortcut built into DTTG be an easier solution?
You can easily create your own template that imports into DEVONthink To Go from Shortcuts.