Hi there - I'm Aly,
I've seen your post and I'm interested. I've had much experience in Microsoft .Net technologies and fortunately, Xamarin Forms is one of my preferred. I understand your concern regarding zooming-in and zooming-out a control inside a ScrollView. I believe I'm capable of completing that in no time (i.e few hours max). I'd like to have a look over the project or even a PoC. Feel free to contact me so we can discuss further details.
Sincerely,
Aly Elhaddad