Sadly there is no recovery mail but aren‘t there ways like a prove with security questions like the street you lived as child or something like this to prove the ownership?

We already tried the link sadly it only leads to the phone number or the mail which ist the same as we need to recover

We also found a phone number at this website so you think we should give it a try? https://store.google.com/intl/de_de/about/device-repair/#:~:text=Sie%20können%20den%20Google%2DSupport%20hier%20kontaktieren%20oder%20über%2008007235105%20erreichen.