In unrelated random thoughts, NurdRage and Nile Red are some of my favorite YT'bers
Muriatic is like a pseudonym for hydrochloric. If you see liquid drain cleaner bottled in a second plastic bag on the shelf of a local hardware store, that is probably sulfuric acid and is much stronger than most other stuff. That's useful for lots of things like a few steps away from dissolving gold or epoxy. The combo or bulk may raise some eyebrows. I like to dissolve epoxy chip packaging to view the silicon die and etch the metal layers off... for example.
I've never seen it in a big box store, but small mom and pops type hardware stores here in California have had it around. It seems to be part of a small distribution network and comes from Mexico.
Nuts. Never seen H2SO4 used for drains. They don't call it "oil of vitriol" for nothing. You can actually test a distillation of pure sulfuric because a drop will burn through a paper towel in seconds.
Drain cleaner can also be lye based, or a mix of potassium hydroxide and sodium hydroxide. Also, every container should have its actual ingredients on the bottle, I wouldn't assume anything you intend on using off label.