Just a thought: I am reading this after posting a message to the group about the same problem. I don't like the idea, but at least it should be possible,
The idea to use google keep widget as this has all the functionality(voice,text,photo,drawing) and get these into joplin via the API.
Maybe a possible step to get something useable,
Now I use Google Keep on the phone and the desktop to move stuff into Joplin.
I just saw this in this group and now think this is interesting; maybe I am going wrong.
keep script
"[SOLVED] Importing from Google Keep - #31 by pluraldon"