try this, when importing to unity from blender make sure that on the transform area on the export tab the apply scaling section has fbx unit scale and make sure in the same area you have the apply transforms checkmarked
youtube video didnt work but this booth product made it possible to make the bouncy glasses, just drop whatever glasses you like into the prefab and just edit physic bones !
https://mimihouse.booth.pm/items/3855573?ref=jinxxy