In 2010, Electronic Frontier Foundation launched a website where visitors can test their browser fingerprint.[14] After collecting a sample of 470161 fingerprints, they measured at least 18.1 bits of entropy possible from browser fingerprinting,[15] but that was before the advancements of canvas fingerprinting, which claims to add another 5.7 bits.

If I'm understanding that correctly, that would give ~14.6 million unique fingerprints just based on your browser. That's a lot, but also tiny compared to the billions of Meta users. I'm a little skeptical that they would be able to determine a user is from the EU without using IP or cookies.

Edit: If they block users who's fingerprint matches an EU user, and their IP comes from a known VPN service, then they could likely get pretty good accuracy. I wonder if there are any North Americans getting blocked while using a VPN.