Agree with you, OsmAnd is practically unusable for me due to the ancient UI. I hated it every time I used it.

I found Organic Maps to be a decent modern alternative. It’s open source and uses data from openstreetmaps as well, but it’s a million times less cluttered.

You might not have heard of the formats but you’ve definitely listened to them. For example, Youtube has only served audio in aac and opus for years now. Most instant messaging apps also use opus during calls to reduce bandwidth usage. And those are just some big examples. Basically almost any online service has dumped mp3 in favor of aac and opus since they’re better in every way (in the sense that they have better quality at the same bitrate as mp3, so you can reduce the filesize by a lot and still preserve the same audio quality)