We are in process of developing a custom command set following this link and ended up in a road blocker as our organization is very strict on github usage. Downloading required components like phantom.js itself failed due to restrictions here and facing issues while setting up the dev environment.
My question, is there any other way to develop such extension without yeoman/gulp? Maybe a silly question but am having this challenge in my extended SP dev role in addition to my usual role.
Any pointer like articles or how-to may help me & others like me.