Ok, I think you have three options:
1) Write the stuff yourself. I once did that using Qt, worked quite well but cost me a lot of nerves. You create some display widget and draw an image within that. If you want interactive control over the program you probably have to work with signals and slots and possibly several threads, a main thread, a capturing thread and a display thread. You can look at the source code of various projects, but think of the licensing terms.
https://github.com/openastroproject/openastro
https://github.com/GuLinux/PlanetaryImager
https://github.com/chmorgan/sharppcap (C#)
You could of course use some other GUI-Toolkit like GTK or TK, or work with opencv like you do, but there I'm completely lost.
2) If you know python, there is a python wrapper for the SDK. This might make the visualization easier.
3) If you like to live dangerously, you can try the julia wrapper which I wrote for the ZWO SDK:
https://github.com/AlfTetzlaff/LibASICamera.jl
You have to install julia, add the Makie package, my package and follow the given example. This runs at 20fps@1280x960 with my old USB2 cam and reaches about 200fps for small regions of interest. Currently there is no support for the raspberry (because I have none), but with your help I could add it in some minutes. Windows *should* work, but I haven"t tested it properly. If you are willing to invest a few hours, feel free to test :)
