Does anyone know any good examples of such algorithms? Can they be implemented entirely as a post-fx?
I cannot speak for SSDO since I’m not familiar with it, but I am using SSAO in my project. I don’t have the link for it, but I believe what we are using right now is a modified version of the one made by @artgolf1000. This one is implemented entirely as a post process, which is - as far as I know - the norm for SSAO. If you are looking for really high quality ambient occlusion, you might have to bake something yourself. Best of luck.
take a look on this Alchemy ambient occlusion