IonicModal Highlight Backdrop-Elements for Walkthrough/Tutorial

Hello togehter,
I try to do my own Walkthrough for my first Ionic-App. I first used the ng-walkthrough but at some point I realised that´s not what I was looking for.

So now I am using the ionicModal-directive and that´s really fine. Now I like to highlight some of the elements under the backdrop for the user. For example “With button + you can add something to your todo-list”. Then I like to highlight the ±Button with an “hole” in the backdrop of the ionicModal.

Does anybody has an idea how I could do that or if this is even possible with ionicModal and the use of the backdrop?

Thank you in advance