Simply the fact that they harbor known harassers like LibsOfTikTok would be enough to de-federate pretty much any other fediverse instance. Why would their moderation have a free pass just because they're big?
Text is very light and compresses very well. While instances may risk having scaling issues with photo and video, text should be very easy to archive forever.
It's been going that direction for a while. Even if we stated, the discourse quality in Reddit overall has been going down. Many of the "fun" subreddits have lost their point and have become shitty collections of short-videos.
For example take a look at r/HolUp. It used to be a very fun subreddit, with a very specific type of content, but now it's just shitty videos that have nothing that make you think "hold up a minute".
The OpenStreetMap website isn't really menant for general consumption. It's more menant as a databse that other services can build upon.
For Android I recommend the excellent OrganicMaps, but you can also use Magic Earth (proprietary). Both are built on top of OSM data.