On mobile, you can do interesting things with Header Enrichment, which helps even more.
IPv6 should "just work", but it seems there's fingerprinting available.
That leaves residential IPv4, which you can solve with some coordination between site owners.
This seems to say - Yes?
https://www.sans.org/reading-room/whitepapers/testing/paper/...
https://en.wikipedia.org/wiki/TCP/IP_stack_fingerprinting
Once you get some sort of fingerprint, then all that's needed is for one site to share with another and they're back to tracking across devices and sites.
On mobile, you can do interesting things with Header Enrichment, which helps even more.
IPv6 should "just work", but it seems there's fingerprinting available.
That leaves residential IPv4, which you can solve with some coordination between site owners.
This seems to say - Yes?
https://www.sans.org/reading-room/whitepapers/testing/paper/...
https://en.wikipedia.org/wiki/TCP/IP_stack_fingerprinting
Once you get some sort of fingerprint, then all that's needed is for one site to share with another and they're back to tracking across devices and sites.