Why an ISO? Because Apple’s restrictions prevent checkra1n from running natively on Windows. The Linux version, however, is highly compatible. By burning the ISO to a USB drive, you can boot any Windows or Intel-based Mac computer into a Linux environment dedicated solely to running checkra1n.
Version 0.12.3 of checkra1n was a significant milestone. It introduced: checkra1n 0.12.3 iso
M1 Mac Compatibility: It introduced preliminary support for Apple Silicon (M1) Macs, though Windows users typically use the ISO method to avoid hardware-specific hurdles. Why an ISO