For those running macOS Sonoma in virtual machines for testing, I found a workaround to enable beta updates within the guest operating system: https://github.com/insidegui/VirtualBuddy/discussions/194#discussioncomment-6406771
Upgrade to Sonoma Beta 3 within VirtualBuddy? · insidegui/VirtualBuddy · Discussion #194

I can't seem to figure out how to upgrade a working Sonoma install in VirtualBuddy rather than downloading a full restore image and starting from scratch. Am I missing something simple?

GitHub
@_inside I downloaded the full InstallAssistant.pkg and ran it inside the VM and it was able to update. I used Mr. Macintosh’s helpful links to get the download: https://mrmacintosh.com/macos-sonoma-full-installer-database-download-directly-from-apple/
macOS Sonoma Full Installer Database. Download Directly from Apple! - Mr. Macintosh

Download macOS Sonoma full installer with one click straight from Apple! Every version of Sonoma Beta & Final available all in one place!!

Mr. Macintosh