Opera software provides Opera Portable for 12.x versions on this page for download, to install Blink/Chromium based Opera on a portable device you need to run the Opera installer, click on Options and choose ‘Stand-alone-installation (USB)’ option. Today, Opera desktop team has released new Opera Portable Installer for developer 18.104.22.168 and is available to download.
Opera Portable Installer
The portable installer, which provides stand-alone version by default is a new and rebuilt Network Installer with UI designed for portable installations and it automatically detects portable drives and suggests installation to those devices by default.
You can download Opera Portable Installer for developer 41 by visiting this link.