Thanks for the guide, much apperiated. However I ran into a problem which I suspect is a bug - after following your steps to set up 2-way sync with either dropsync/ folder sync to my SD card storage, my Obsidian android app was able to view the vault, but any edit / new folder created will pop up an error “failed to save file . FILE_NOTCREATED”.
I am following a similar thread describing the issue (unfortunately no replies yet) in the bug forum. Has anyone encountered this issue beore ?
EDIT : I found an alternative to my case - in the Android device, change the vault location from SD card to Internal helped. Not sure why.