Yes but it's a lot of work to integrate with literally over a hundred different TLD registries to provide full spectrum domain registration coverage. And it's not just technically difficult; there's lots of work to do from a legal/biz dev standpoint as well.
Much easier to integrate with a reseller and have them do a lot of that for you. Then you can only worry about the big ones (e.g. Verisign for .com), and maybe slowly onboard to additional ones over time.
It seems they have a relationship per AWS's docs [1] for handling certain TLDs. In particular this calls out using Gandi to verify transfer of .*.uk domains. I'd be very surprised, however, if that that deal is tied to consumer pricing.
Much easier to integrate with a reseller and have them do a lot of that for you. Then you can only worry about the big ones (e.g. Verisign for .com), and maybe slowly onboard to additional ones over time.