While the idea of a version of Genshin Impact
No legitimate repack from trusted groups (e.g., FitGirl, Dodi) exists for this game because it's always online.
True "high compression" (using tools like FreeArc, KGB Archiver, or 7-Zip with ultra settings) can shrink a game by 20-30% at best. For Genshin Impact, that would mean 50-60 GB, not 10 GB.
Use the official launcher’s pre-installation feature before a big update. This allows you to download the data in chunks over several days rather than all at once.