What's the requirement if any for app.medplum usage in a local environment, and what is the replacement for it when some of the demo applications in the repo either link to there or have docs that tell you to create something there? Is my self hosted instance tied to a medplum account?

for those who self-host there is no tie to app.medplum.com or the hosted medplum service. The apps built on top will need to be configured to point to the self-hosted service instead of the cloud service.

You can find directions on how to run the Medplum App on your

localhost

here: https://www.medplum.com/docs/contributing/run-the-stack#run-the-medplum-web-app

Thanks! That was roughly what I thought was happening, but wanted to confirm.