Can't login on iforgot.apple.com

I'm trying to regain access to an old (ancient) Apple Account of mine because some hackers in China found my password (password reuse, it was in an unrelated breach) and are registering a lot of devices and installing software.

I know my Apple ID email and password. I have access to my Apple ID email.

I deleted my rescue email address and I can't regain access to emails sent there. I don't know my security questions, I think I just put random strings into them.

Whenever I try to login on iforgot.apple.com I can successfully submit email and password but I then get asked my security questions and I'm stuck. If I fail inserting the security questions I get sent a code on my rescue email.

I called Apple support multiple times and they can't help but I know there must be a way in, given the hackers managed to login with my details and I'm pretty sure they can't get my rescue email nor bypass the security questions. This sounds like either an API or some combination of device / software which can bypass this check.

I can't generate a support pin unless I can provide my security questions or receive emails. Apparently Apple is uninterested in people registering devices with stolen credentials (I offered them to just delete the account asking for confirmation).

I'm thinking of sending a GDPR request to at least delete my personal data, but any tips appreciated.

From my cursory research, it looks like you can regain access to an account you have been locked out of without recovery options, after a mandatory waiting period:

https://support.apple.com/en-us/HT204921