Have you not heard of a router? Sure i have an internet connection but i wouldnt have to. Lots of people have subnetworks that are isolated from outside network access, and my router would still be able to stream from my computer to my laptop even if my internet was down or i unplugged the modem. The last time they did scheduled maintenance on my internet thats exactly what i did, i streamed things that i had previously downloaded and saved on a different computer.
Im sure you could find a usb c camera that could easily be obscured or pinned to a lapel or otherwise disguised for cheaper than the price of a pair of smart glasses, or even just wear your phone on a lanyard around your neck with the screen facing your chest. People might think its weird but noone is going to second guess it unless your phone is in your hands actively pointing at them.