Meros is still under development and occasionally runs Developer Testnets. Anyone can participate, as long as they compile their own Node.
For guides on how to compile Meros, please see https://github.com/MerosCrypto/Meros/tree/master/docs/Development/Compilation.
Meros is seeking out developers to contribute to the codebase! If you wish to help out, please read the Style Guide, and then pick an item from the TODO.