You can make a Ventura bootable USB installer by first formatting a 16GB or 32GB usb as Mac OS Extended (Journaled) and naming it Untitled.
After downloading the Ventura Beta 1 installer (which so far is nameless, even though we now know it has the name Ventura) you can run this in Terminal to make the bootable USB:
sudo /Applications/Install\ macOS\ 13\ beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled
The command for future betas will probably change to
sudo /Applications/Install\ macOS\ Ventura\ beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled
and then with public release (or even release candidates) to
sudo /Applications/Install\ macOS\ Ventura.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled
After downloading the Ventura Beta 1 installer (which so far is nameless, even though we now know it has the name Ventura) you can run this in Terminal to make the bootable USB:
sudo /Applications/Install\ macOS\ 13\ beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled
The command for future betas will probably change to
sudo /Applications/Install\ macOS\ Ventura\ beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled
and then with public release (or even release candidates) to
sudo /Applications/Install\ macOS\ Ventura.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled