Hi, I found this suggestion for allowing sandboxed iframes (without allow-same-origin) to have an assigned service worker through adding an srcworker attribute to the iframe:
<iframe sandbox srcworker="./service.js" />
I and a few others in the thread linked above have expressed support for this feature but I am unable to find an issue in whatwg for this feature. I've simultaneously been looking for a good excuse to start contributing to web browsers and this seems like as good an opportunity as any to do so.

I recognize that this would be an addition to the specification and so I would need support from at least two implementers. How can I go about getting that support? Should I open up feature requests/PRs on the browser engines? Should I first make a feature request on whatwg/html and then get support from implementers? Thanks!