Gluon Maps is not an app, but a library. The usage policy of osm should be followed by the user of the library. But indeed, it would be good to make this more clear and I totally agree the policy should be followed, so if we can help with this, it would be good.
Or we can remove osm by default as a provider, so that developers using Gluon Maps explicitly have to add it, which increases the chances the policy is clearly read, understood and followed.

Regarding the license, https://github.com/gluonhq/maps/tree/master/samples/mobile looks like an app to me :) .
Regarding distributing osm tiles, for example https://leafletjs.com/ samples use mapbox

Ok, we'll remove that app.