I've been using the Browser extension for years and it is incredibly helpful. We use it to debug scripts on customer websites by making them resolve to our local instance so that we can test fixes quickly.

I would recommend some sort of graphic on the homepage to explain what Requestly does though, as you mention it can be confused with Postman when it's entirely different. Maybe an animated flowchart type graphic showing how a browser request to X is redirected to Y based on some Requestly rule.