Missed PIDs? Really or just hidden

Hi
My question: Are some missed Pids like fuel really missed or just hidden?
I did something similar at work with GPS, INS and photos. I have read the hole bt stream with a port crawler and picked the nessesary stuff and brought them together.
So if I do the same here, read the bt stream on the com port from the connection, I will find my information? Because in the garage they read all infos via obd. So the info exists, but no one knows where, because its so secret?! Or is it a question of the used protocol? Does each car send everything or really just the info I can get via my vgate icar pro?
I have tried as explained in the forum some ways to get the fuel level. No data. But as I wrote, the info exists.
Thanks for your answers.

Fuel level is one of those PIDs that many vehicles do not give with standard PID but instead use their own, manufacturer specific one. There is no public database of manufacturer specific PIDs that we are aware of.

Thats what I found on your homepage.
But my question is more, is that info somewhere on the stream or isn‘t. I can read all the data over a port with a special app on w10.
I asked some manufacture of ODB Adapters if they know more. Sometimes they write anything about deeper data for a brand.
I will see.
The problem is, realdash is that cool, that I want a solution…!

If you know what the PIDs are, you can always write a custom XML for your car. See instructions here:

https://github.com/janimm/RealDash-extras/tree/master/OBD2