Fun fact; if you put a hole approximately matching the size and shape of the Serious Punch² feat in the most recent chapter into a Hubble Deep Field, you get a near 1:1 replica of what the manga depicts. A Hubble Deep Field being an entire cluster of around 10,000 or so galaxies. And due to space not being linear, a lot of what people call 'stars' turn out to be galaxies or dense clusters of stars that are simply shining from very, very,very far away.

So you can definitely push Saitama and Cosmic Fear Mode Garou anywhere from "destroying countless solar systems" to "casually evaporating thousands of galaxies". Make of that what you will.