Here in Germany the addresses you provide for these things needs to be "Ladungsfähig". And just a mailbox doesn't fulfill these requirements.
The only alternatives are renting a shared office space with at least a desk for you and someone that answers the phone and handles mail.
Or convincing a lawyer that you can put their address together with your full legal name (which also a lot of people don't want to have known publicly) there so that mail arrives there.