Great points about noise, and you really hit it on the nose with your final point—I've heard of a mental model of Twitter being likened to tapping a tuning fork and seeing who resonates (https://twitter.com/kevinakwok/status/1076967914580918277).

The most fun (and probably best) self promotion is done with fun in mind—Tom Critchlow's post on small b blogging vs. content marketing comes to mind (https://tomcritchlow.com/2018/02/23/small-b-blogging/), and he extends his thought with this one (https://tomcritchlow.com/2019/03/12/strange-attraction/). I also liked Matt Webb's post on this (https://interconnected.org/home/2020/09/10/streak).

Please excuse me if I'm being pedantic, I'd change the "hope" point to "showing a person"—even if it's just an email to a friend, cold emailing someone who you quote, etc.