Yes! The IONOS Agency Partner Portal can be used without publishing a listing in the Agency Partner Network. IONOS partners can communicate with their clients via the Agency Partner Portal at any time and manage their projects without having a profile in the Agency Partner Network. It's up to you if you want to appear in the Network. However, publishing a listing helps potential clients find you.
The Partner Network is visible to everyone, even if they don't have a partner account. So anyone visiting the IONOS website can search for agencies, freelancers, and web professionals.