Welcome to the Wefugees Community and thank you for your question.
First of all, the "Duldung" is not a residence permit but a "temporary suspension of the deportation". People who are supposed to leave Germany, but some issues are currently preventing a return/deportation, are getting this kind of paper. If you are actually hiding from the authorities since a while, it will not be easy to get a work permit. I am not sure, how the authorities react if you register yourself now. I would highly recommend you to get some support in a migration counselling office. Those kind of services are free of charge and confidential. You don't need to worry that the social workers will report you.
I will also link two of our experts here. Dear @MBEon-Sophie or @mbeon-Bernd, do you have any advice or can you add some information?
All the best,