I (from EU) would like to move to Germany start a company and work for my old IT employer. Is it feasible?

Hello, I'm an EU citizen (Poland) trying to move to Germany. Following my partner. I'd like to keep working in my current company, also based in eu. In such case they'd need me to possibly start one person company in Germany and hire me as contractor.

Is it feasible, complicated, legal? I don't speak german yet. It's important to me that I have a valid health insurance. Could anyone share some advice or let me know who should I contact? Some German lawyer or an accountant? I'm a bit hopeless with those things. So I'd really appreciate any form of help, thank you.