With respect to the idea of hosting personal websites without using hosting companies, why does it have to be port 80. Port 80 is what commercial hosting uses, but this proposal is fundamentally different from commercial hosting. I'm not sure I understand why using an agreed-upon high port would not be an acceptable alternative.

As for non-rooted Android not allowing use of port 80, this is just one symptom of the larger problem of not allowing the computer owner to have root privileges. And letting an advertising company have them instead. IMHO.

Unrelated perhaps but it is possible to forward port 80 in Android. For example, I forward tcp/80 to a computer running NetBSD. This can be done using an app, e.g., NetGuard. TLS zealots might want to try this sometime and observe some of the unencrypted egress traffic.

Thought experiment: Imagine you make a salary or other financial gains by applying what you know in the subject matter area of X. Someone comes along and proposes that they want to teach more people about how X works. What is the likelihood you will respond with something like "no one really wants to know how X works". You want to maintain the status quo because you understand that an information asymmetry between people who understand how X works and those who do not must exist in order that you may continue to be paid for or otherwise profit from your knowledge.