Please consider easing configuration override from os_prober
The adjust_timeout function overrides both
timeout when another OS is found. This makes it "impossible" to have a silent boot. I know you are trying to make this "friendly" for regular users, but would you consider at least NOT overriding
timeout_style and setting
timeout to 1. So at least we can set
timeout_style=hidden from config and have that respected. This confuses many power users as the behavior is against GRUB's official documentation.