https://www.google.com/search?client=firefox-b-d&q=ffmpeg+rt...
https://github.com/aler9/rtsp-simple-server
https://news.mistserver.org/news/71/An+introduction+to+encod...
Some of the back end software pieces to do it are not very dissimilar from a typical 'zoneminder' install on amd64 debian. Yeah I edited that in after I forgot to include it before hitting the post button...
on something like a raspberry pi 3b+ or 4 you might get good results by using a video frame rate around 5fps. Or even if you went down to 2-3fps that would be functionally equivalent to a constant stream of still images, depending on what the stream is needed for. If it were a security camera that needs to see peoples' faces the frame rate could be too low, a moving person might pass through the frame without any good shots of their face.
If you have lots of network bandwidth you can do a great deal with ffmpeg by not transcoding the video from the format it's acquired from, which is very helpful on systems with limited CPU power.
https://news.mistserver.org/news/71/An+introduction+to+encod...