#OpenStreetMap is a user-created detailed map of the entire world:
Like Wikipedia anyone can use or edit it, and the content is free and open. There are no ads or trackers either.
For apps, we would recommend OsmAnd for Android/iOS: https://osmand.net
(OsmAnd is also available on @fdroidorg )
I don't recommend maps.me.
It was bought several years ago by Russian tech giant mail.ru who filled it with advertising and lots of user tracking.
(There is a better version on f-droid called something generic like "maps" which has the tracking stuff stripped out.)
mastodon.at is a microblogging site that federates with most instances on the Fediverse.