picayunish could describe someone concerned with trivia.

But I, too, like bloviating to describe the expression of such a person best of all. And, to beat it all, have heard myself bloviating so many times and realized later, with regret, that that was exactly what I'd been doing!

But picayune is a good word for trivial things, and picayunish is a comical adjective form in that you can see part of "p----unish" in it!

Bloviating regrets,
Wordwind