The ELM 327 is just a common IC used to interface the OBD II with a PC or mobile phone. It has absolutely no clue about the data sent in either direction. That's the job of the software you use.
Next, the OBD II port provides lots of information in a standardized, known protocol. That means the way to read out for example RPM, speed and error codes is the ...
I see the ODB port as a great and easy hook up for dash cams. 1) some makers of the 3rd party hardwire kits are already using this connection option 2) for dash cams with motion sensors or 'G' sensors (this feature recognizes the car being hit or bumped, depending on the sensitivity selected) - having the unswitched power is a must. Particularly for devives ...
Thanks to EU4/5, most modern motorcycles offer direct OBD II functionality through generic scan tools. You will need to buy a brand-specific adaptor/harness, and many of the more advanced OEM functionality such as diagnostic mapping will still require the OEM computer tools, but OBD is on bikes now, and has been for several years.
This information is proprietary. Pro Scan tool manufacturers spend many thousands of hours sampling/deciphering vehicle data and reverse-engineering from OEM tool communications. This is the very value of their product.
They would be unlikely to publish this data to the general public.
It's like asking Colonel Sanders what his recipe is.