This is what a typical Impressum should include. I will ask you to fulfill that information, and add more if you consider:

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  The legal name of the company or the individual responsible for the website.
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  The full physical address (a P.O. box is not enough).
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  The responsible person (e.g., the legal representative or owner).
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  Contact details, including a valid email address and phone number.
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  The commercial register number and the relevant local court, if applicable.
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  The VAT identification number (USt-ID), if applicable.
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  Any required references to regulatory or supervisory authorities, if your business is subject to special licensing or professional regulation (e.g., lawyers, doctors).