Performance Optimized Realistic 3d Avatars

Anybody know where I can find realistic looking 3d avatars that can be customised to use in Unreal Engine which are not performance heavy like Metahumans? I tried various software like ReadyPlayerMe and Mixamo but they are all too stylised. If Im building a multiplayer experience which has to potentially host 100s of avatars on screen at the same time, Metahumans is not an option right? Even with LODS. Any ideas? Problem is our environment is photorealistic, so using stylised avatars inside a realistic environment doesn’t look great.