In the LL we use OBS for assembling and delivering complex live streams: combining webcam video and pre-recorded footage, using the chromakey filter to live-key a subject in front of a 3D background, launching gifs and soundbites in realtime to add to workshops and lectures. These links will get you started with this tool.
Here are some links to get you started with OBS.
If you want to use OBS with Zoom, you will need to use a virtual camera app. The most complete solution (and the only one we've found so far that does a good job routing audio too) involves the suite of tools built by NDI.
links of interest related to scripting for OBS (and developing, since you actually need to use the developer references given the fact that there isn't really a great scripting guide):