You can use an Ubuntu or Debian live CD as a pristine environment to create an Electrum wallet on. A live CD distribution is a Linux distribution that can run from a removable medium like a DVD or USB drive. For historical reasons they are called “Live CD” distros sort of like how we call movies “films”.
For example download the latest debian live CD, verify the ISO using the sha25sums and related signature file and then burn it onto a DVD or write it to a USB. I recommend using the amd64 XFCE version.
Boot from the live CD and click on the black terminal icon. Then grab this script and run it:
wget https://github.com/AbdussamadA/electrum-install/raw/master/electrum-install bash electrum-install 3.3.3
Replace 3.3.3 with the latest version of Electrum as mentioned on the Electrum website download page.
The script will install the correct dependencies, download electrum and verify the GPG signature. If the signature checks out it’ll install Electrum on your live CD distro for you. You can disconnect from the internet after the installation is complete.
Because live CD distros are readonly you’ll have to do this everytime you boot from it.