It's often done in situ - you might find someone to do it for you? If it's outside that is. Adding the aggregate on top is a bit shit as it tends to fall out. Washing the cement/matrix off the top few mm is the better method but you need to get the timing right.
Would anyone know of where to get exposed aggregate paving? A bit like this:
All I can seemingly find is awful looking resin paths, or this one tile, which is smallish and a bit pale :
https://www.claybrookstudio.co.uk/trousdale-tread-aniston.html