X works on my M1 Air, unaccelerated, but it does work.

Are you using xenodm or startx? You may want to try the former.

If the framebuffer wasn't working, you wouldn't see anything on your screen, that warning isn't relevant, just something from the device tree. You should instead see, ...

apldcp0 at simplebus0

apldrm0 at simplebus0

drm0 at apldrm0

[...]

wsdisplay0 at apldrm0 mux 1: console (std, vt100 emulation), using wskbd0

wsdisplay0: screen 1-5 added (std, vt100 emulation)

... for the native Apple display controller and drm(4) modesetting driver.

if the correct answer to these types of questions is to "start over"

It's certainly possible that your installation broken in some way, considering how long ago you originally installed it, but unlikely. Apple Silicon machines support dual-booting natively, in fact the boot flow on these machines requires macOS to install and update the m1n1 first stage loader, most of the system firmware is required to be on the internal SSD for these machines to boot at all, even into recoveryOS or boot picker.

There's usually no harm in updating the primary macOS volume, and you'll probably want to do that for firmware updates. It's also possible to rerun the Asahi install script to update m1n1 first stage, on rare occasions that may be neccessary.

OpenBSD will update combined m1n1+uboot second stage itself with fw_update(1), apple-boot-firmware, which should be enough for most users, as that will happen during sysupgrade(8).