The clear answer from "Fritz" on 27 June 2024:

Hello,
Thank you for your enquiry and your interest in our products.
You are interested in the differences between the versions of the FRITZ!Box 4060.

There are no technical or functional differences between the national and international versions of the FRITZ!Box 4060. There are only differences in the scope of delivery, e.g. power supply units for use in different countries.
for use in different countries.

Information on the FRITZ!Box 4060 can be found at
avm.de/products/fritzbox/fritzbox-4060/


The manual, knowledge documents and downloads for this FRITZ!Box can be found in the service area of our website:
avm.de/service/fritzbox/


AVM products are available from well-stocked electronics retailers in your area as well as from stores such as Saturn, Media Markt, Conrad, Expert and online shops such as Otto, Amazon or Alternate.

You can find a list of AVM specialist retail partners, including a search function by postcode, at
avm.de/products/online-shops-and-haendler/


Kind regards from Berlin
Your AVM Product Consultancy

There is actually no such thing as an international model any more (https://www.deskmodder.de/blog...) but for models with built-in modems, the standards for Germany were different from the international model.
Otherwise there are no differences.