They use Chromium (or any other browser) not out of choice but because they have to in order to participate in third party video conference sessions. Of course it’s best to reverse engineer the video conferencing clients and do HTTP requests directly without a headless browser, but I presume they’ve tried that and it’s very difficult, not to mention prone to breaking at any moment.

What’s surprising to me is they can’t access the compressed video on the wire and have to send decoded raw video. But presumably they’ve thought about that too.

There are no packets on the user's API. But under the hood everything is sent in packets, numbered, ACK'ed and checksumed. The maximum packet size supported by IP is 64KB, as they say. I'm surprised the kernel supports that because I'm not aware of any real device that supports packets that big (Ethernet Jumbo Frames are only 9KB), but I guess it must.