Delegate-CH

Delegate-CH is an HTML meta tag or HTTP header used in web development to delegate high-entropy User-Agent Client Hints to cross-origin or third-party domains 

those that are sent with every request (Low Entropy Client Hints) 

those that must specifically be requested by the server (High Entropy Client Hints)

It works alongside or similarly to a Permissions Policy to safely grant third parties access to specific client data

sources/further_reading 

https://github.com/WICG/client-hints-infrastructure

https://51degrees.com/blog/implementing-user-agent-client-hints

https://docs.scientiamobile.com/guides/implementing-useragent-clienthints

https://datatracker.ietf.org/doc/html/rfc8942