They would not be able to go to magical locations on their own.
Neither wands nor broomsticks would work for muggles. As to floor powder, unfortunately I don't think we're privy to enough specifics of it in order to make a fair statement. As we never see a muggle use floo powder, I'm left to assume that this, too, would not work for them.
Something like a portkey would work, because it has already been charmed to bring a person who touches it to a specific location.
Otherwise, muggles have no magic and therefore wouldn't be able to use items that require magic, or find locations hidden from muggles.
This is very much unlike
squibs who, while not having explicit magic to use a wand, do normally have enough magic to use magical items in their lives. We know this because Filch, a squib, successfully uses a Secrecy Sensor. They aren't equatable to muggles because they obviously know about, and can find, wizarding locations.
I hope this helps.
