As mentioned by Crow, Android’s built-in isn’t up to the job … so …
EDIT: Using GBoard’s microphone input works remarkably better than I remembered. It also syncs the voice input language with the current GBoard language.
Speechnotes | app | web |
Speechtexter | app | web |
Both of the above apps let you share the transcription.
I shared it directly to my Android Mobile Obsidian app and had the choice of inserting it into the current open file or choosing a different file.
Thus there is no need to convert into “.md”
Both apps work offline(lower quality)
Their web versions:
Speechtexter also lets you share.
Speechnotes needs copying & pasting.
So now that it is in your Obsidian Mobile you would need to sync it to your Obsidian desktop version with syncthing, foldersync or such - great info here.
Personally I might do it the old-fashioned way 