NC that larger piece of glass looking material looks like foundry slag.
I am not sure that glass will work for gunflints and most of the stuff in the first bunch of photos looks like a form of glass. I have some gunflints that were made out of late 1800's English flint that was used for ship ballast and dumped when they arrived in America and my true English flint looks more like dacite than obsidian. Not an expert but have had a little contact with the English flint.
I make self bows on thursday nights with a bunch of re-enactors who are hard core smoke pole shooters and I will talk with them about it.