@stefanjank You can create a Tab Component with the dialog configuration as shown in the below screenshot.

You can make a generic tab as well, if required to specific the no of tabs required.
Steps:
1. Read the no of tabs and based on that display the tabs to be configured. This will be optional.
2. Configure the different tabs.
3. In the sling model, either you can fetch the value based on the hard code field Name i.e.

and write your logic to read and create the custom Map or List from the tabs multifield list.
4. Or you can iterate based on the no of tabs and make it dynamic using the for loop, but in this case the name field should be name something like ./items_1 and iterating in the loop you can fetch the respective values.
5. Return the list from the Sling Model
6. Iterate the sling model from sightly.
Hope this helps!
Thanks