When can I get an iPhone/Android/whatever mobile version of Ripcord?

Probably never.

• $2 is considered "a lot" for a mobile phone application. Most mobile phone users are willing to pay exactly $0 for their mobile phone software.
• Companies that develop and profit from mobile phone software often charge $0 for the app on the phone itself, but charge for the services that make it useful -- Uber, Amazon, etc. You pay for the service, not the app. Another variation of that is virtual gambling games.
• Ripcord is not a service or a gambling game.
• I (the author of Ripcord) don't use mobile phones for very much. I don't care about mobile phone software, except for getting maps and notifications about emails and messages. I don't know what makes a good mobile phone application. I don't have any interest in making one for myself.
• I'm not going to make software that re-sells your data or displays ads so that I can make money from mobile phone users.
• Assuming anyone even paid for it, I wouldn't want 30% of the revenue to go to the app store gatekeepers.
• The entire design of Ripcord is built around the desktop paradigm. Menus, windows, mouse, keyboard. Not touch. Not small screens. There is no way to re-use nearly any of the Ripcord code to make a mobile phone application out of it.
• There are already free phone apps that would do the same thing as Ripcord. And they're probably better than whatever I could make for phones.
• Google and Apple will remove third-party clients from their "app stores" at the behest of large services like Slack or Discord, and even state so in their agreements.