Wow! What an amazing post to read! Thanks @lemouth for regularly bringing awesome stuff related to black holes, dark matter and dark energy. :)

Primodial Black Holes can be a good candidate for Dark Matter as they were created in first sec. of the Big Bang. Probably they were created by the primordial soup of quarks and gluons due to fluctuations of the inflation and way before the first atoms were created.

Probably they were earliest massive (also smaller) objects of the universe. As you said the smaller ones were evaporated quickly due to Hawkings radiation (and as that radiation is inversely proportional to the mass of the black hole).

However, the massive ones may be still present, most probably in the center of galaxies. And according to Hawkings equation, they are probably very much colder and radiate very less (very much less than what mass they attract, reverse is true for smaller/minute primordial black holes). Because of that it will be little difficult to detect them through their radiations. But we have already detected complex minute things like gravitational waves. Maybe in future we may also detect dark matter inside these black holes. ;)

Your post really enhanced my knowledge. Thank you so much @lemouth. :)