Hi Jasmin,
Yes, it is possible to enhance the Pick List form with extension fields by SDK.
What is you need to do is that extend the BO SiteLogisticsTask with some extension fields and the logic in the script code as well; then you need to add them into the required form via right-click on the BO.
This is requiring your SDK user admin model enabled first. And once you have done, it will effective for forms: Unload list; Put-Away List; Move List, Load List and Pick list.
Hope this help you.
Regards,
Qiang