@Ronny Cornelis,Thanks for posting in Q&A.
From your description, I know that you are looking forward a way to manage mobile devices without Microsoft account.
Based on my research, for Intune, Corporate-owned dedicated devices is the only enrollment method that does not need a Microsoft account to manage mobile devices, but this enrollment will set devices as shared model.
For Knox, please be sure that you meet the requirements below to manage mobile devices:
1.A Samsung Knox account.
2.Samsung devices running an appropriate Knox version.
3.An EMM provider that supports Knox Mobile Enrollment.
4.The correct firewall exemptions to allow network traffic with the Knox Mobile Enrollment server.
5.A supported browser (Google Chrome, Microsoft Edge, Mozilla Firefox).
Non-official, just for reference.
Thanks for your kind understanding.
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