ARIN has an IPv4 /10 dedicated to IPv6 enablement with NRPM 4.10 being the policy for how that works. Both of our IPv4 /24 blocks are from NRPM 4.10. None of the other RIRs have a similar program. RIPE still theoretically gives a /24 to new organizations but it's only a single /24 compared to ARIN where you can get a /22 and then apply for more. ARIN's waitlist also moves faster since most of the legacy IP space which can be reclaimed was given t o North American organizations.