Just finally found a use for the Omega after having it for so many years.
I tried set it up via web interface but that was a mess... the cloud registration page url is a 404 and then the firmware update just never finished. I connected via SSH and got up to here:

BusyBox v1.25.1 () built-in shell (ash)

   ____       _             ____
  / __ \___  (_)__  ___    / __ \__ _  ___ ___ ____ _
 / /_/ / _ \/ / _ \/ _ \  / /_/ /  ' \/ -_) _ `/ _ `/
 \____/_//_/_/\___/_//_/  \____/_/_/_/\__/\_, /\_,_/
 W H A T  W I L L  Y O U  I N V E N T ? /___/
 -----------------------------------------------------
   Ω-ware: 0.1.5 b130
 -----------------------------------------------------
root@Omega-8975:~# oupgrade
> Device Firmware Version: 0.1.5 b130
> Checking latest version online...
> Repo Firmware Version: 0.3.2 b233
> Comparing version numbers
> New firmware version available, need to upgrade device firmware
> Downloading new firmware ...
/usr/bin/oupgrade: local: line 1: not in a function
--2021-09-11 20:39:39--  http://repo.onioniot.com/omega2/images/omega2-v0.3.2-b233.bin
Resolving repo.onioniot.com... 52.217.137.125
Connecting to repo.onioniot.com|52.217.137.125|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 9699493 (9.2M) [application/octet-stream]
Saving to: '/tmp/omega2-v0.3.2-b233.bin'

/tmp/omega2-v0.3.2-b233.bin        100%[=============================================================>]   9.25M   719KB/s    in 14s

2021-09-11 20:39:54 (672 KB/s) - '/tmp/omega2-v0.3.2-b233.bin' saved [9699493/9699493]

> Starting firmware upgrade....
Saving config files...
killall: watchdog: no process killed
Sending TERM to remaining processes ... uhttpd device-client onion-helper udhcpc avahi-daemon mountd ntpd ubusd askfirst udhcpc dnsmasq oupgrade Terminated
root@Omega-8975:~# logd rpcd netifd odhcpd
Sending KILL to remaining processes ... askfirst
Switching to ramdisk...
Performing system upgrade...
Unlocking firmware ...

Writing from <stdin> to firmware ...
Appending jffs2 data from /tmp/sysupgrade.tgz to firmware..
.
Writing from <stdin> to firmware ...  [w]client_loop: send disconnect: Broken pipe

Then it rebooted - now it doe snot show up as AP anymore.
On power up it blinks fast, slow, then solid but no AP showing and it also does not connect to the router (checked connected devices on router).

Not sure what next...

Thanks!

Realized I can connect via serial super easy on mac - this is the result:
https://pastebin.com/raw/ThHYgeYw

I entered firstboot -y; sync; reboot and now its AP popping up again. did the wifi setup via ssh this time.

Seems to all work now...

I'll leave this here, maybe someone finds it useful.

Some more info here is that the serial drivers offered for mac are crashing on M1 big sur but are apparently not even needed, the omega shows up as /dev/tty.usbserial-0001