Hi @meteka,
Thanks for your post and welcome to the Cesium community.
We have a previous discussion thread about steps to get Cesium working on Flutter with WebView Using Cesium on Flutter - #2 by Matt_Amato
This may be enough to answer your initial questions and get you started, but if you have more questions please feel free to follow up and we would be happy to try to help.
Note, another thread asking for developer feedback on using WebView with Cesium was also just opened on the forums, but with no follow up discussion yet. Best framework for a performant CesiumJS mobile app?
Best,
Luke