Could just be the anthropic principle at work : in a ridiculously large universe, we live in a tiny fraction of it where local fluctuations in the respective distributions of matter and antimatter have happened to favor matter. (And the observable universe is even smaller than that.)

Well, if we suppose all the anti-matter is in those black holes, we kill two birds with one stone. It’s ridiculous, I know, but your remark made me realize that an anti-matter black hole is essentially indistinguishable from a ‘normal’ one.

Both of those are pressureless, so they could be dark matter but not dark energy.

Except that primordial black holes are ruled out (as 100% of dark matter) by various observational bounds, and antimatter would be just as visible as normal matter and not "dark" at all.