[ISL]

Fig. 7 is definitely where it's at -- I had the same question, as a camera is not just a lens, but a camera obscura[1], both the lens and the 'dark box' within which an image is formed.

My impression is that their metasurface lens has approximately a 1 mm focal-length. In the diagram, the light appears to pass through an intermediate focus at that distance, which they then pick up with another optical system for control/convenience.

I don't see anything that would, in principle, prevent using the metasurface lens as a component of a tiny camera. Nature has certainly evolved imaging systems that are smaller and modern sensor technology permits wavelength-scale pixels. With maximum charity, it appears that this lens/methodology might be used to yield a ~1-2 Mpx imaging system with a 1 mm f/2 optical system.

The claimed advance here appears to be that the combination of their lens and processing yields higher quality imaging at these physical scales than prior work.

It does indeed appear that in combination with a tiny imaging sensor, this lens could yield a camera the size of a large salt-grain.

This entire field of engineering appears to be in a golden decade; it may not be too long before we start seeing metasurface optics in consumer imaging products.

[1] https://www.etymonline.com/word/camera