UPDATE:
I reread @AdanApost a few times. He calls these fasteners a "BINDING BOLT".
Internet also calls them "BINDING POST & SCREW" and "BINDING BARRELS & SCREW".
The tee nut description from the other post threw me off a bit.
Below are some screen grabs from Lowes and McMaster as an example.
What's interesting is in the reviews of the Lowes option, someone used a pair of the fasteners to fix the visor in their Honda.
@AdanA also mentions the size range of the bolt: 3/4" to start, ending at 5/8" when cinched.
This gives me more info to source the hardware. Will report back.