https://www.thetradedesk.com/industry-initiatives/unified-id...
https://www.verizonmedia.com/insights/overcoming-identity-he...
And probably a dozen other ID solutions out there that require you to be logged in and thus have some first party data to match you with.
Honestly I'm not sure what the value proposition is for the user if it's not required to log in, so who knows what the uptake will be.