You can use this repository to generate a new Rails application without having to install Ruby on your machine.
It works by using Docker to generate the Rails application for you. Docker takes care of installing the right Ruby and Rails versions for you, so you don't have to worry about it.
You need to have Docker installed on your machine. You can find instructions on how to install Docker on your machine here.
To generate a new Rails application, you can run the following command:
bin/rails-new myapp