How do you learn to share what you do, when you're not used to sharing at all? Should one accept that noone will read 99% of what one shares and just use sharing as a way to record and reflect on own process?
Yes, 100%. Almost no one has found either my public code or my writing useful, but the process of writing and documenting has been tremendously useful to help me clarify what I _actually believe_ at that point in time. This is the primary benefit.
That said, a few projects have taken off unexpectedly and clearly helped some folks, and I've received a few cold emails from folks who somehow ended up on my blog, and all have been pleasant conversations!
One thing I recommend is trying to lower the threshold of what is acceptable to publish. Publish scraps, publish "today I learned", publish "look at this stupid thing I discovered" stuff. Gradually your threshold will rise, but one mistake I see people making is the belief that they have to publish finished projects and novel-quality writing in order for it to be worth it. Nothing could be further from the truth.