Extra thanks to @DidierMalenfant for bringing Agate to my attention and to Cloudron.
I am excited by the potential for Agate+ to replace solutions like Ghost etc for simple sites where a CMS is overkill, without resorting to things like Jekyll and Hugo.
Those apps are great of course, but sometimes you just don't need the complexity and overhead.
Even the very wonderful Surfer app involves authoring static html by hand or in some html editing tool. With Agate+, fire up an instance of the app, open File Manager, create your Markdown content, bosh, live dual protocol website/capsule.