Fedora Encrypted Root With Automatic Key Unlocking

Fedora’s installer will happily set up an encrypted install with root-on-lvm-on-luks (/boot is still unencrypted. Secure Boot might be handy here still). This is supported and works out of the box. However, while I’m present when I reboot this machine, it is also headless (no keyboard or monitor), so typing a passphrase at boot is problematic. But no problem, you can have up-to ten key slots for a LUKS partition, right?