The inclusion policy meantions that the app id should be based of a domain under the developer’s control. The definition of domain name is very broad, so I don’t know what counts.
Does it have to be a whole dns-registered domain (nobodyfornothing.com) or would it be enough to use a subdomain (nobodyfornothing.github.io)?
And what requirements do I have into keeping the domain under control (e.g. I doubt some 8 year old f-droid app still has controll over the domain connected to the application id)?
In case I do need to own a whole domain: are there any cheap favorable tld?