1. Getting exposure Right now from that video, you are a faceless rapper with no real incentive for a fan to subscribe, or follow on social media. You should either look into making a cheap music video that attaches a face, or some visuals to the track which allows you to address the audience after the video for what content and notifications you can get at each social media channel. After that, as long as you keep up the quality, and can maintain some degree of a regular content posting schedule (1x a week/month/quarter), you can build a regular audience.
2. Song topic ideas If you want to stick with the tech theme, stay with it. I think this song came from a 'write what you know' place, so you can do more with it i.e. more workplace/professional annoyances, or any other common shared experience for your fanbase you are trying to build. Be relatable, and write what you know.
3. Monetization You already have a patreon, and are working on swag. That's already what high level youtube/musicians do as the endgame, unless you see yourself having appeal for concert/performance settings at a convention or something. If you want to build more fast songwriting skill, you could sell short songs on fiverr or something for a bit of cash and forcing yourself to keep working on your talents. Focus on your fanbase first, and worry about monetization later. I don't think you are at a critical mass yet where a delay in a monetization route means lost money.