What is missing is shared workers support (and producing output from console.log in web workers). Of the two, shared workers would be a particularly useful feature, as it would in theory enable different browser tabs to utilize a shared, potentially resource hungry script, as per the Mozilla description at https://developer.mozilla.org/en-US/docs/Web/API/SharedWorke...
The devs at Apple claims that this use case is not relevant and/or better served by Service Workers (which is even less supported). Not sure I understand their reasoning. https://bugs.webkit.org/show_bug.cgi?id=116359
I started to find the compliance tables on MDN outdated. I am not sure how they are being updated but my guess is that it is manual and needs to be revisited.
Are you referring to service workers? I've been using web workers on iOS for years.