To manually download the Full Version ( about 17 GB ) of macOS 26.2 Tahoe and Not allow it to Automatically Launch
In the Terminal application >> Finder >>> Go >>> Utilities >>> Terminal
Copy and paste this command below and press the return key
softwareupdate --fetch-full-installer --full-installer-version 26.2
If successful the last line appearing in Terminal should read something like " Success " for something like that
Check in the Applications folder for " Install Tahoe app "
You can copy the Application to another External Drive
Then copy from the External to the Internal Drive >> Application folder of that computer
Provided the Other Computer Qualifies to run macOS 26.2 Tahoe
You ready to go and install Tahoe on that computer
As for making a Bootable Installer of Tahoe
As far as I know
The only reliable way to make a Bootable Installer is via the Terminal command
Tahoe macOS 26 via Terminal
sudo /Applications/Install\ macOS\ Tahoe.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
Where, MyVolume is the name of the Destination Drive which will be Full Erased when the above command is executed
You may also what to give Terminal application Full Disk Access
