Njalla is the only service I'm familiar with: https://njal.la/

No first hand experience, however.

They’re pretty expensive, and the nature of the service means that if they disappear, they have ownership of your domain and you have no recourse to get it back.

Worse: if Njalla decides you shouldn't have a domain - for any reason whatsoever, including "we don't like your web site" - they can seize it, and you have no legal recourse.

This is not a hypothetical, by the way.

It could be useful just as a landing page to direct users to a .bit domain.

You mean the "domains" that >99% of users can't even resolve, which can't be used to send or receive email, and which you can't have SSL certificates issued for? Don't be daft.

A self-signed SSL cert could work for it. There may also exist other solutions that we are not aware of.

99% of the target users will resolve it if they want access (by installing the necessary browser extension).

As for system emails, etc., they can come through any regular domain.

That's the nature of 'private' domain registration used more commonly, at least to some degree for many private registrations. If you read the agreement, you are transferring your domain registration to the privacy service, and they forward stuff to you. I don't know what happens if they disappear, however.

It'll be a pick one problem (secrecy, control) until say the big browsers support .bit domains directly doing a lookup on the block chain.

Porkbun accepts crypto

I can't really understand the desire to be completely anonymous. Isn't GDPR protection or some paid privacy protection enough?

GDPR applies when using a service that has KYC, and it applies only to EU citizens. As for paid privacy services, they get altogether ignored by aggressive sites like BeenVerified.

In contrast, when offering a service that is politically incorrect, at least in some geographies, it is useful to remain anonymous as the service provider. It is also then useful to not collect any unnecessary user data that could put the user at risk due to a data leak, although an email address is commonly still required for each user.

The crypto-privacy-coin world is at an altogether different level wrt privacy than the rest of the world. It is a lot closer to being the real deal.