But unfortunately No in regarding the ton of work that could be necessary to support Cloudron.
There is another important aspect as to why Ubuntu is the underlying platform for Cloudron. A lot (if not all) hosting providers are offering servers with this os preinstalled, which makes it easy to get started with Cloudon. If MicroOS would be the (only) supported choice then Cloudron users would be limited to hosting options which either provide it by default, or allow admins to install their own os (which could be a challenge for some).
If I remember correctly both Nebulon and Girish are former Suse employees, so I'd wager they would be biased towards MicroOS otherwise 😄