Personally I just install Dokku onto the machine, it replaced all my Heroku (and competitors) uses.

Additionally, you still keep the full ssh access to the machine if you ever need it.

Hey I'm building a managed service platform (not quite an app store!) on top of Hetzner -- would you be interested in trying it out?

Contact is in my profile but I'd love to have some more people kick the tires and tell me what they want built the most.