In a variety of mods there also recipes with glass, maybe integrate glass scrap / broken glass as a extra scrap material?

I feel like if you have crushing industries installed, maybe you can crush the scrap to get something. I would just make them make the crushed ore variants at a lower rate than the ores themselves.

I may add glass scrap. The reason I haven't yet is because sand fits the same role as glass shards would, so it's a "pointless" item. But I may add it as an optional variant for glass-related items. I'll try it out and see how it feels.

As for crushing scrap, I view crushing as similar to recycling, where it doesn't reverse chemical reactions. So iron plates may recycle into iron scrap, but iron scrap wouldn't recycle into iron ore, as that would reverse the effects of smelting the ore.