Resurface exposed aggregate concrete patio
If you don't have to make the overlay "very thin" and the patio is structurally sound, there's not a whole lot of "bonding" needed - a 1-1/2 - 2" thick overlay on a sound, solid concrete substrate will happily sit there, unless it has voids to encourage spalling (by filling with water and freezing) in the winter. As it happens, that looks like a pretty good bet for bonding to (with very exposed aggregate) though it would probably be advisable to pressure-wash it to remove any loose material, and probably also acid-etch it to improve bonding and further clean it up.

Thin is generally harder to do well with masonry materials.