I have figured out to give an object url to a local file selected through an input type file. If this file is glb it is appended to the scene as I want. If it is a gltf it cannot be appended, and an error on console says:
BJS - [15:03:01]: Unable to load from blob:http://127.0.0.1:8887/ca4a2c45-95e1-40a3-8488-1d3a33a0f0c5: Unexpected magic: 1969300091
I think this can be due to its accompanying files. How to load a local gltf file which has a .bin file and possibly other assets too.
Note: all of the files are in the local file system.