I have thought about this for years, ever since ISPs in my country started advertising "unlimited whatsapp" on otherwise data limited plans. It would only work for text and not images or video, but it would have been good enough for general web browsing.
I meant that the ISP would block wpp image and video traffic, but would allow text through. It has been several years since this happened, so I may be misremembering.
I belive you're misunderstanding what TCP-over-X means. If you can exchange messages, it means you could exchange bytes, if you can do that you can send any form of data, including HTTPS which is an application over TCP. HTTPS could then include video and images, encrypted and therefore difficult to specifically block.
GP was asking specifically about sending images and video as wpp images and video (which is why he mentioned them being re-encoded). I suspect that sending that amount of data as wpp text messages would run you into some sort of trouble, but maybe not! Somebody above posted an implementation of this idea, and they mention that using it could get you banned which is unsurprising imo
