People mostly dual-boot so they can access software they need that isn't on macOS, but it isn't available on ARM Windows either so why would Apple care to foster a nascent competing platform?
Additionally, the importance of this use-case (from Apple's perspective) has decreased significantly since they originally developed Boot Camp. While I'm sure that many people do run Windows on Mac hardware, the percentage of Mac owners who do this is likely dropping significantly (if I remember correctly, there was a statistic about this in a comment on another thread about ARM Macs).
Boot Camp does not work with Linux on Intel Macs, so the question in this case would be whether the low-level bootloader would allow unsigned/third-party code or whether it would be locked-down like on iOS devices.