Q. (See prior question 1959). Is there any prohibition of pas yisroel when it comes to wheat flour based cereals?

A. The gezeira of pas akum applies only to to bread products containing one or more of the five major grains: wheat, barley, oats, spelt or rye, that have the form of bread or tzuras hapas. (Shulchan Aruch, and main commentaries Y. D.112). Corn and Rice Cereals are, by definition, not bread items.
There are different opinions of contemporary Poskim in regards to Cheerios and the like; many are lenient.
Horav Shlomo Miller’s Shlit’a opinion is also to be meikil.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a