question about deployment to heroku with waypoint

[mjcc30]

Hello everybody!

I'm trying to deploy a phoenix app on Kubernetes with waypoint and I see that we can use a Heroku custom buildpack to do this :
hashicorp/waypoint-examples#34
https://www.waypointproject.io/plugins/pack

I also know a site that uses this build pack I think :
https://github.com/montrealelixir/website

I understand a little how to use waypoint but I don't know how I can use Heroku build pack with it, nor how Heroku build pack works.

Does Doe anyone have any idea or some information about how to deploy a phoenix app with Heroku buildpack and waypoint?

Thank you very much!