Living in Germany/ Mining in Poland

Hello everyone!!

I actually live in Germany, Berlin.

I am about to start GPU crypto mining (not trading) activities. They will generate yearly income in BTC or other lite coins like ETH, Ergo, etc. for less than 22.000 euro / year during 2021 as per actual conversion and less than 50.000 Eu in 2022. I mention this data in regards to the business registration that I believe could fall into the small business: Kleinunternehmer.(small business)

However the mining machines will be based out in Poland, but I live and pay my taxes in Berlin. I have a full time permanent job as employee in Berlin, so beside the approval of my employer, might I need a private business registration in Poland too?

My main question would be about how to declare such assets in the tax report, as the activity of generating such coins from crypto mining economic activity.

Also about the proper company/sole trader registration document required.

I would like to have my taxes in order.

If you have clear answers to my questions and could help me with this kind of issues or point out to the correct person I will be very happy.

Thank you!!