Light theoretically would travel at c in a vacuum, but I think a vacuum is practically impossible. So light doesn’t ever travel at lightspeed? And therefore it does “experience” a tiny amount of time between emission and absorption/reflection?
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What do you consider a practically possible vacuum? The vast majority of the universe is not just interstellar, not just intergalactic, but actually enormous voids between galactic clusters. The average density of atoms in the universe is really low (one google result says “around 1 atom per 100 cubic meters” which seems about right to me.) A crude estimate is that a photon must come within about 1 wavelength of an atom to interact with it. If I did my math right, that translates into about 1 light year on average between interactions, assuming all the matter in the universe were spread out evenly, which it’s not.
And note that those interactions aren’t always, or even usually absorption or reflection. I responded to another commenter on this topic — optical refraction (which is the phenomenon that leads people to say that “light slows down in materials”) is a very complex process where the EM field of the moving light causes electrons in nearby atoms to shift a bit, which in turn generates transient EM fields that combine and distort the original field. But this isn’t absorption. A crude analogy would be if you play a pure musical note near a harp – the harp strings vibrate and the result is a sound that isn’t exactly the note you generated, but the harp didn’t completely absorb it and re-emit it.
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