Help: Looking to downgrade to Android 9

[Jeb]

I'm looking to downgrade to Android 9 from Android 10 on my US variant of the Asus Zenfone 6. I tried looking it up on the site, but the downgrade file there states it's only available for the WW version.
Does anyone have a download link or guide to do this?

Here's my system information:

[kikoly]

Your firmware version is WW, download it and downgrade.
https://www.asus.com/Phone/ZenFone-6-ZS630KL/HelpDesk_BIOS/
https://dlcdnets.asus.com/pub/ASUS/ZenFone/ZS630KL/UL-ASUS_I01WD-ASUS-18.1220.1909.194-1.1.1-user.zi...