3D web viewer Coding expert

Need to create a website with similar functionality to:

Sketchfab
Nira
Arskan

The requirements are simple. You will have IN-DEPTH knowledge of one of the following systems / standards:

1 .gtlf files, and the google compressor Draco.
2 .3dtiles from Cesium including using Draco
3. Traditional gaming engine (unreal?)
4. p3dw format

and you will have full understanding of the requirements that are needed to implement a fully functioning web-based 3D model viewer.