The latest BIOS is version 303 "UM3402YAR.303" (Release Date: 09/05/2023). All items posted here will be specific to the model number and BIOS version described here (BIOS 300, 302 were known working). Some things might be specific to Arch Linux but should be generic and portable to other distributions. There are no guarantees and should you wish to try any of this out it is assumed to be at your own risk.
The sound does not work out of the box (at least not on Arch but I am guessing for most Distros as well).
The patch 0001-ALSA-hda-realtek-Add-quirk-for-ASUS-UM3402YAR-using-.patch is required to be applied to kernels older than v6.4 to ensure that the Realtek sound device is properly bound to the Cirrus amplifiers. If you are using kernel v6.4 or newer this patch is not needed.
The ssdt_csc3551.dsl file can be used per the instructions found in the file header. No need to patch the DSDT, this is a stand-alone SSDT that is easily u