An Azure service that provides geospatial APIs to add maps, spatial analytics, and mobility solutions to apps.
Bing Maps does not support offline mode.
With Azure Maps it is possible to self-host the web SDK as it's available via NPM. I believe it can work offline with a bit of configuring, but it won't have any access to any of the map data, so you would need to have a local tile layer available for offline use. I've done this before with version 2 of Azure Maps, I'll have to try out version 3 (lots of map style changes that may impact things).