What can I build, parallel to building in public, which will amplify my journey and grant me exposure?

Think of this
Dan Rowden's Ilo.so which is not solely his main product, but it reinforces his BiP journey with network effects and viral loops
Typefully, a tool made by Mailbrew's @Linuz90 and @Frankdilo. As Typefully (a side-product, when compared to Mailbrew) grows, the two gentlemen's story piggybacks as well.
Classic example: Basecamp launching their books, Ruby on Rails or countless other side-projects that reinforce their main story
My personal examples:
The Build in Public Cheatsheet I'm building (thanks for reading it!)
🏅 Want to suggest an example of yours?