When I mentionned that “I can confirm it is not realistic to self-host a tile provider”, it’s because I tried to run maptiler : it maxed out my CPU for 2 hours before my disk got filled while trying to generate the tiles from OSM data (and it was just for France)
Edit : Anyway, I don’t think this should be in Immich’s scope. Simply providing an easy option to switch tile providers would allow people motivated enough to host maptiler to use it