okay - how about a few other angles?

https://stats.labs.apnic.net/ipv6/ - per-country, and within a country, per-asn eyeball statistics, collected from online ads - not just mobile!

https://www.facebook.com/ipv6/?tab=ipv6_country - per-country, albeit with a mobile-heavier bias (as you hint)

https://www.akamai.com/internet-station/cyber-attacks/state-... - collected from their content delivery network - tends to show lower adoption than the other metrics

i would point out that "all mobile phones have IPv6" isn't true globally, but it is the reality in some countries, yes.