Sure, ionizing vs non-ionizing but millimeter waves do do localized, penetrating, heating and the intensity of millimeter radiation from 5G is orders of magnitude stronger than that from the Sun.
Is it consequential? Probably not, but the OP's original comparison of 1000 W of Sun vs. 100W from a tower and nW from cell phone is disingenuous.
Shorter wavelengths have higher photon energy. It's the short stuff that you have to worry about.