AppSource simulator isn't running, instructions to 'run your own' 404

[johnnydecimal]

The instructions at Selling Your Saas-based Teams Extension / Step 2 fail.

1. The service that we've pasted in to .env, https://bgmonetizationwebapi.azurewebsites.net/api/Subscriptions/CheckOrActivateLicense, isn't running.
2. The instructions to host your own are a 404.

I'll dig around the repo and find the host-your-own link but this makes it feel like these labs are abandoned. Are they?