Earlier quoted context omitted.
If you need to create your own tiles, I'm not sure how this changes anything. I can't seem to find how one would go about generating one's own tiles for this platform in their documentation. Did you find something to that effect in it?
Author here. You should be able to first download OpenStreetMap tiles in PMTiles format ( http://github.com/protomaps/pmtiles ) and then write out a new augmented tileset in the same format. It's a use case I want to have first-class support for, but the tooling doesn't exist yet.
To elabore on my comment, I was more wondering about how I generate those tiles from non-tiled raw PBF country extracts on Geofabrik.