Do you also build your own kernel, glibc, dnf, openssl, pipewire/pulseaudio, systemd, ffmpeg, ffmpeg extensions, gtk, gcc, rustc, llvm, python, coreutils, ca certificate bundle, x11/wayland, clang, nodejs?

I'm guessing no. So your overall security posture is line 3, where you're trusting fedora to be the gatekeeper for you.