I know that this method allows an ARM iMac connected to the Internet to get RosettaUpdateAuto.pkgThere are plenty of guides if you search for RosettaUpdateAuto.pkg. e.g. https://tinyapps.org/blog/202103270700_backup_rosetta2.html
Download and install Rosetta 2:
% softwareupdate --install-rosetta --agree-to-license
Find path to installer:
% grep RosettaUpdateAuto.pkg /var/log/install.log
Copy installer for safekeeping:
% cp /path/to/RosettaUpdateAuto.pkg /path/to/backup/dir/
They don't have to! You can copy it to a usb-key and pass it around to the machines without internet.I know that this method allows an ARM iMac connected to the Internet to get RosettaUpdateAuto.pkg
The difficulty is that these iMac of the company are "not allowed" to connect to the Internet.