How should I Build in public? Do you know what data should be shared and where?

Depending on what you want to achieve.

Most people built in public as marketing method. If that the case then you need to think if you customer will view be interested with the posting or not. Basically if you are in this category "built in public" is another marketing method.

If you built in public to show case your process and built trust within communities and potential users, then you need to show mistakes and how you fix it. Approach it like how you will talk about things you doing with your close friends.

There is no clear method on how to do this, it all depend what your final objective is.

You can checkout this article about built in public : What Build In Public really about and Why you should do it

honestly, share all of it. you never know what will resonate with someone else.

I wish you much success,
Scott

I recently started building in public with my SaaS and I've share systems we've set up unique to our team, hiring our first intern and the onboarding process, our vision/values all with screenshots directly from our Notion team page which seems to get some good attention.

i would be interested to know where builders find their first 10 customers

I think MRR and mistakes are the most crucial concerns for everyone.
MRR represents whether the project is successful and mistakes are something all builders want to learn from.