+1 for OBS. It's very easy to use (add different inputs and click record). External monitor is a must. A good (as in > $20) microphone is worth investing in to avoid annoying noises, in particular computer fan noise which is likely to be an issue given you'll be recording video.
Just yesterday I was researching how to connect an external camera like Canon EOS M50 to use as a overhead projector (so you can show handwriting/diagrams like a whiteboard), and it seems possible using https://github.com/v002/v002-Camera-Live but I haven't tried yet.
One last recommendation (to the OP) — keep the videos short. Video is great as the introduction material and to show more complicated bits, but if you can use text + code samples, I think you students will appreciate.
Also allows you to set up your layout for the video-windows, with presets/templates, iirc.
Recommend you have a second screen open on the obs, though, so you can easily manage what’s up or not.
Would also be a good idea to start experimenting early to figure out some good layouts etc depending on how you want to present the material.