If I want the maximum anonymity while buying it?
I used [large american registrar], but switched to a small one in my country because I wanted to pay a local business. I found it from somebody’s compilation of companies that offer a TLD for my country, and I just picked the recommended one in that post. It was the one that charged the least.
Keep in mind that with a smaller registrar you won’t be able to get a TLS cert using the “do some shit with my domain records” method - you’ll have to always install the nginx/Apache etc. plugin for Let’s Encrypt
You don’t have to use the registrar’s DNS system.
I use LuaDNS. They even offer a fully functional free tier that might be enough for your needs.
They have an API that can be used with certbot, and you can manage your zones with git.
Ah right, sorry, switched things up. Indeed, I also use my registrar’s DNS system, but if I switched to something that has an API supported by certbot (e.g. dns zones that cost 0.5 eur in large cloud providers) it would work.
I use cloudns for nameserving. It’s free