From personal experience, I can share that my middle son, who applied to three UC schools, was admitted to UCSD in the ICAM major, to UC Irvine in the computer game science major, and was waitlisted at UCLA for electrical engineering. He was an independently homeschooled student from California with a 2230 SAT, 730 Math II, 710 Lit, 610 Physics, no AP scores, 39.5 units of community college, and he did not meet the a through G requirements in geometry, social science, and fine arts.
He did not have straight A’s in his college classes, and in fact had three B’s. He was not a particularly academically strong student ( had math through calculus one in the spring of his senior year, and had only one semester of foreign language at the community college). We were very happy with his admissions results. I have no insight into how the UC schools evaluated him for admissions, but it’s clear that holistic admissions is playing a larger role in the UC system these days.