Dear @curt,
Installing certbot on systems running outdated versions of Python should be universal enough to work on any Linux and maybe even others like BSD, macOS and Windows WSL.
While we have only tested it on an outdated Debian system, you should not hesitate to try it on Ubuntu. Likewise, we will be happy to hear from the community about other targets / platforms where this could have been applied successfully.
With kind regards,
Andreas.