Hi @wojtek.swiatek ,
My initial thought is to use Data Collection task to request for an input via Email or another communication method to look for some inputs from outside of XSOAR. The benefit of utilizing this is the respond will be tied back to the task/playbook so you don't need to manually look for the response.
If you use Webhook integration, it will create a separate incident instead of feeding into the existing incident which can be managed but it will involve extra developing and routing.
Let me know your thought on Data Collection (https://docs-cortex.paloaltonetworks.com/r/Cortex-XSOAR/8/Cortex-XSOAR-Administrator-Guide/Create-a-...)