Sorry for the delay on this one
I knew there was something odd about Asus ALC294 but I missed the possible solution from last year and went off around the wider internet for information
There was a post on here in Nov 2020 from a user with a ROG Strix G512LV
No sound from laptop's speakers - #4 by bogdancovaciu
based on a confirmed patch solution for ASUS ROG G512LU on Bugzilla
https://bugzilla.kernel.org/show_bug.cgi?id=206589#c7
( If the other solution does not work out the patch file option is worth trying, but it might not have the correct HDA Verbs for this laptop. I only know the basic theory of how HDA verbs work so I would not know how to work out hex numbers for HDA verbs if the suggested values did not work out)
The modprobe patch used by Manjaro OP is also confirmed on Askubuntu to work for Asus ROG Strix G15 G512LW , G17 G712LU and G712LV - No sound ALC294 Asus ROG Strix 512 Ubuntu 20.04.01
So I suggest:
run hdajackretask, click Remove boot override and reboot system to unmodified state with no retasks
Then use this command to add the modprobe option
echo 'options snd_hda_intel model=asus-zenbook ' | sudo tee --append /etc/modprobe.d/alsa-alc294-patch.conf
reboot again to make sure the model option is loaded