Welcome, hope you would be positive addition to community.
Driving license from any country is valid for 6 months. You would need authorized German translation while driving. If your stay is up to 1 year, that validity can be increased by extra 6 months. Office responsible for that extension is Führerscheinstelle (driving license authority) in your city. In some cities you need an appointment and in others you don't. Better take there someone who can speak German with you.
For stay more than 1 year, you need to convert your licence to German license, no matter from which country it is. Again you would go to Führerscheinstelle with passport size photo, German translation of original license, passport and certificate of your personal registration in your city (Meldebescheinigung).
To get a conversion for Pakistani or UAE license you need to clear both theory and practical tests. The registration to both tests is only possible through driving school. Now, you would have to convince the teacher that you can drive and that you don't need to sit in theory classes and you don't need driving practice. You may have to drive few hours though.
A new one is indeed around 2000 Euros but this conversion would be less than 500 Euros, because a lot of money goes into driving practice and theory classes.
BUT
I would suggest you to drive a bit and get some practical lessons. Driving in Germany is different from that in Pakistan. It is disciplined to extreme and very fast on motorways (Autobahn). In Pakistan, we don't care about signals, speed limits, signs, line and lane etc but that's not the case here, and bad habits don't leave the person easily. There are zones inside city 30km/h, 20km/h and a bit complex rule for foreigners "
right before left". Check the link for details. There are training areas (Verkehrsübungsplatz), check which one is near you and have some practice before driving on roads.
and beware of German chachus and chachies driving on Autobahn
Conversion is cheaper. You don't need all the driving practice hours and theory classes. I have written the process for gentleman, have a look. It is possible to get between 400 to 500 €.