Ruby is developed on Linux and written in the language - C. Ruby runs on Linux and other UNIX-like operating systems, macOS, Windows, DOS, BeOS, Amiga, Acorn Risc OS, and OS/2. This cross-platform support allows developers to use Ruby on many different systems, making it very flexible and accessible to a wide range of users. Technically, Ruby can be used on microcontrollers, but this requires an interpreter (virtual machine). So for real projects on microcontrollers, it is better to use C. Ruby developers typically use macOS or Ubuntu as their operating system for work. Technically, it is possible to develop on Windows, but there will be quite a few nuances with the support of various libraries, etc. (it might be a bit better if the project is wrapped in a Docker container). Currently, Ruby and Rails perform quite well on ARM architecture (Apple M-series chips).