Is there any way to add a custom button in the tabbar of Xamarin.Forms, like it's seeable on the mock below?
Thanks in advance. Cue.

Is there any way to add a custom button in the tabbar of Xamarin.Forms, like it's seeable on the mock below?
Thanks in advance. Cue.

You can use relative layout to add the tabs in Xaml, If you need any coding help let me know I'll help you to design this layout.
I came across this question while looking into implementing a very similar tab bar. There is one other option I've found to do this without writing those hefty custom renders yourself. Check out Sharpnado. It provides a variety of possible customizations for a Xamarin.Forms tab bar.
There is also a blog post on implementing a few options, complete with sample code you can clone.