My current domain registrar has an EPP API where I can manage my domains and records.
I'd like to extend certbot or in some way write a plugin to be able to automatically, not manually, use certbot for DNS-01 challenges.
I couldn't find information about this in the documenatation.
It's not, that's why I created this thread in the 1st place.
It's a cheap, not prominent registrar and provider using the EPP to manage domains and records.
You might have wanted to mention that in your post to spare me the effort. I'm not able to read minds and thus could not have known you already checked those options.
Looking at Extensible Provisioning Protocol - Wikipedia, I'm not sure EPP is even the protocol you're looking for. Maybe there are some relevant extensions, but just looking at the EPP, it really seems to be a registrar thing, not for modifying the DNS zone, where the latter is required for adding and removing the required TXT RRs.
Copy an existing plugin and modify it to your own needs. That's all I can say about that. Maybe other users have more input, but this is just what I can provide.
The easiest way to implement a DNS provider for yourself is often to write a single script (python or bash etc) and call it as a custom create TXT record script. Various ACME clients support this method and it can be easier than implementing a full certbot plugin etc.