Comment by Imustaskforhelp

I had done this in the covid lockdown days as my school was going to online classes.

Droidcam and wo-mic are some good options in this space. Droidcam if you need both a webcam and mic. Wo-mic used to work on lower android versions.

I remember plugging Droidcam to my win 7 (1gb-ram) crt tv computer and then taking an really old mostly junk phone outside and my parents were watching the monitor. It was really awesome :p

Though after an year, I ended up buying a webcam because that unused phone used to get quite heated and was really a finnicky setup to do everyday but It was a very fun experiment that I did for quite many months.

It's been a few years since covid now and I have a mac laptop now but on my desktop I still don't have webcam, and so I also use https://obs.ninja sometimes now

So TLDR if someone really wishes to do this: Droidcam,wo-mic,(https://obs.ninja + OBS live camera option)

I think its a good way to make use of old phones that you might not be using but imo battery life and its consumption seems to be the biggest hurdle imho