EMZ (ZZP) for High Skilled migrant

Good afternoon,
Please tell me the following:
I am a High skilled Migrant (I have been living in the Netherlands for 8 years). I don’t plan to break the contract with the current company and would like to additionally work for a company from Germany while in the Netherlands. The current Permit is for 5 years (until April 2023) and there are no restrictions from the sponsor’s company on the second job - indicated in the permit \\\”Arbeid als kennismigrant. Arbeid vrij toegestaan, TWV niet vereist.\\\” I am currently taking exams to obtain a permanent resident permit/passport (one exam left).
In this regard, I plan to open EMZ (ZZP) and issue an Invoice for a company from Germany

1. Are there other options to combine the two jobs? (For example: request a work permit in Germany). The company (from Germany) is ready to help with this, it is possible to work remotely. It is even possible to sign a permanent German contract.
2. In the event of the opening of EMZ(ZZP), will this not be regarded as \\\”schijnzelfstandigheid\\\” by the Netherlands? because invoices will be issued to one company?

I was going to order an EMZ registration service from you, but I had doubts.
Sincerely,
Sergei