How's the chance that GOG change for ScummVM? Soon?
https://www.gamingonlinux.com/2024/01/scummvm-2-8-0-released-with-new-game-support-and-plenty-of-upgrades/

I'd be nice to have clear and working instructions on how to extract the files from the Mac version to use in ScummVM on Windows, as I can't figure it out.

Just went though this myself, heres how-to:

Assuming you're on Win10 or Win11. You will need 7zip.

Download mac offline installer from GOG
Open the pkg file in 7zip
Extract scripts file (should be at about 1,7 GB for S1)
Rename scripts to syberia.cpio.gz
Open it in 7zip
Extract payload\Contents to new folder
Open ScummVM
Add game, navigate to newly created folder with Contents.

Voila!