It only supports the chrome devtools protocol[0]. chromiumoxide is therefor more like a (limited) puppeteer rust port. Support for javascript page injection is currently being worked on
Out of curiosity how much interest is there in a JS injection utility (written in JS) that walks the DOM, executes events, reports pass/fail/error, has no dependencies, and does nothing else?
[0] https://chromedevtools.github.io/devtools-protocol/