I have no idea to do that.

But probably Maybe my posts will help.

https://dannadori.medium.com/how-to-edit-the-image-stream-for-video-chat-teams-zoom-3acb58669f26https://dannadori.medium.com/how-to-edit-the-image-stream-for-video-chat-teams-zoom-part-2-emotion-analysis-by-tensorflow-819563f17dfehttps://medium.com/analytics-vidhya/how-to-edit-the-image-stream-for-video-chat-teams-zoom-part-3-convert-to-anime-84a6788819d2

These describe the way to send the image to v4l2. And ffmpeg can capture the screen.