It is recommended that you **do not set a password for the `root` user** as this is _safer_ (nothing is 100% safe). But if you **really want to** (_**do this at your own discretion**_), you can log into `root`'s login shell with `sudo -i` and then set a password for the `root` user.
There are two repositories that are maintained by Rocky Linux. One repository provides packages that are specific to SIG/AltArch for SBC enablement. Another repository is basically ELRepo + some Rocky stuff. Depending on your needs, this may or may not be a good thing. Please change this as you see fit.