Neither could the space shuttle but surely that's a spacecraft. Why would it have to leave a planet to count?

Most spacecraft we know of never left the Earth orbit anyway.

It spends it's entire mission above the Kármán line (100km), so it is legitimately in space, and is therefore a spacecraft, like all other satellites.

This video covers the general concept, and even mentions redwire at the end

Air Breathing Satellites in Very Low Earth Orbit (13:12) - Eager Space : https://www.youtube.com/watch?v=vEfatzhHhvg

It's a spacecraft that scoops up air to put into its propulsion system.

There's an annoying lack of details here, but that part is simple.

"air-breathing" is a common term for engines that use oxygen from the ambient air instead of from a tank - also people do this too. In this case though, it's just using the air as reaction mass though. Space begins at a lower altitude than the atmosphere ends so even a space-craft can be air-breathing, in principle, at least.