Yes, people who are:

- Working on hobby projects/sideprojects

- Working on open-source projects

- Selling stuff

For someone to create this example, they would either have to do it in a codebase they don't have problem open sourcing or which is open source, so they do not break NDA's and divulge company info/source code.

How many people are ready to do that?

The conditions of the OP are:

- No demo, independent programmer

- Non-greenfield project

- Non-trivial problem

- Code deployed in production and robust

- Code review, test, testing, PR creation

- Person be willing to live-stream their work and code while building

Which is a pretty unreasonable set of conditions to prove "it works", when the person could read a tutorial and try it themselves.