Thanks for the fast answer!

Some consideration:

LibRAW does support Leica M11 (triple sensor as the Q3, interchangeable lens), Leica Q, Leica Q-P and Leica Q2 (different sensor, fixed lens, and look like the lens iare the same in the Q series, but switching from one to another the behavior is different). Anyway all them use DNG, so I think that some differencies does exists. Probably (just my idea) that the M11 is very similar to Q3, but can't say this for sure.

In any case, without neither an entry of the Q3 in LibRAW (even if identical to M11), the software which uses the library can't understand what camera is and does not act consequently, forcing to manually select a "similar" lens/camera to proceed.

Also using Adobe DNG converter (without compression, of course) the converted file (Leica DNG to Adobe DNG) size is quite different, so I suppose that Leica DNG are in some way not equal to Adobe format.

I'm not an expert of raw file structure, but I believe that something is different.

Again thanks for your attention!

Denebola