Sounds a lot like sandcats (/sandstorm), albeit slightly less ambitious?
It'd be cool to see a service like PikaPods built around Sandstorm as the platform layer, but there's a LOT of work to do to make Sandstorm a good idea to run commercially, and since we aren't running it as such, nobody's really working on those things.
I use Docker images, as provided by the upstream project. So you get the same experience as running it yourself, as well as quick updates.
1: https://docs.sandstorm.io/en/latest/vagrant-spk/packaging-tu...
1: https://docs.sandstorm.io/en/latest/using/security-practices...
One of the biggest things is that Sandstorm prefers to sandbox individual documents versus applications, which mitigates a huge variety of security flaws in apps. In most cases vulnerabilities in apps on Sandstorm are not exploitable when run on Sandstorm.
It also manages most authentication and authorization roles for apps in an integrated way, which requires more integration work than just spinning up a Docker container.
Feel free to hit me up if you want to know more, though it would be a lot of work to make Sandstorm work for your business model at this point. It's cool seeing others in the "make open source web apps user-friendly to run" space though.
I do want to point out that this is from 2014 and we don't use Docker at PikaPods. We use Red Hat's stack, which integrates better with other Linux tools, like SELinux and Systemd.