Mark Kettenis, one of the active OpenBSD developers, reported successfully booting OpenBSD in multi-user mode on an Apple device with an M1 processor. Currently, not all the changes needed to work on M1 are accepted into the main OpenBSD code repository, as they are essentially hacks, however, a start has been made and it is planned to work on support for this platform in the future. In particular, the bwfm driver has recently added basic support for the wi-fi chip Broadcom BCM4378, which comes with Apple devices based on the M1 processor.
Source: opennet.ru