How to make my site compatible with the upcoming Cross-Origin-Isolation changes for SharedArrayBuffer

So I read that there are upcoming changes in Chrome to enable the usage of SharedArrayBuffer specifically "Making your website "cross-origin isolated"". My site makes use of external APIs that don't meet the requirements for this. So what I did was, offloaded the code that uses SharedArrayBuffer into an iframe using a subdomain and added the required headers to that page. Reading a bit more into it now, it seems that I still need to have the top level document served with the required headers otherwise I still get the warning in the console.

Just to clarify, my site now is using the following structure:

• app.website.com -> contains the complete application functionality
• service.website.com -> contains the functionality that makes use of SharedArrayBuffer

I thought that I would be able to simply add the required headers to service.website.com and everything would work properly, but I'm still getting the cross origin warning. Any ideas?

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