Check if a datatype item is in a list

Hi,

I have seen some similar posts but can't figure out how to resolve my issue with the answers in others posts.

I have a list in a page state, and I need to check before adding an item (get with action output) to the list than the item is not on the list.

Here is the action flow (I need to setup the condition) :

Here is what I tried :

I tried with and without "single condition" (see screenshots).

But the last step always seems to ask me for a specific field in the selectedOption (with is a dataType, the same as all item on the list).

So how can I check if an dataType item is in the list ?

Here is the post I already consulted but didn't find answer :

Thanks for any help