I had a similar issue moving from an iOS app to Android for the first time. In your project, you need to move your graphics, etc. to sit under the root folder Assets - in your example, the full path would now be Assets/Sprites. I don’t know whether you explicitly need a folder named Content under there but I had one already in my original projects so my content files were placed under “Assets/Content/gfx”, “Assets/Content/fonts”, etc. The Content.RootDirectory setting in my game class was simply “Content” - MonoGame seems to automatically treat Assets as the root folder for Android content.
HTH,
Mex