Replying to myself - this needs to be native code really. We are using various .Net UI frameworks, but the mapping is all via Mapsui and Brutile.MbTiles. The current renderer we have is not ideal as it is quite slow and incomplete.
It's cross platform (Linux, OS X, Windows, and BSD) [1] and written in C++. There are bindings for Python/Node/C++.
There is also maplibre-native [2] (which suports Android and iOS as well as Linux/Windows/macOS).
Mapnik is usually used to pre-render raster tiles on a workstation or server. MapLibre Native is a native alternative to the MapLibre GL JS library (both forks of the no-longer open-source MapBox equivalents) for rendering vector tiles in the browser.
[0]: https://mapnik.org/
[1]: https://github.com/mapnik/mapnik/blob/master/INSTALL.md
We basically need a "tilesource" for XYZ PNG based tiles that is fed on the fly from vector tiles and is cross platform enough that it relies only on something like Skia.