The Raspberry Pi Foundation has brought the option to install an OS on a Raspberry Pi 4 or Raspberry Pi 400 without needing a secondary computer. While not a headless setup, Network Install brings greater versatility to the two single-board computers.
https://www.notebookcheck.net/Raspberry-Pi-4-and-Raspberry-Pi-400-receive-a-new-feature-courtesy-of-a-beta-bootloader.598834.0.html