(a little long winded, but I'm hopefully other's might find this info helpful too)

The Mastodon server list is here. All the public ones seem to have a "Browse Directory" link. Without joining or signing in, this lets you "explore" the various Mastodon servers. It seems to let you browse their users' public profiles. From their you can click on a user and see their profile and a feed of their public posts. So it's all accessible on the public web.

No, I'm not familiar with Bastion. At a quick glance, there seems to be several things with similar names. A bit different spelling, Bastyon is a social media based on the Pocketcoin blockchain, which seems more like what I expected to find. The Bastion spelling seemed at a glance just to be DeFi lending.

I've tried Friendica and Diaspora a while back. They both are federated Facebook-like social medias. You can host your own "pod" server, or join someone else's, then the servers de-centrally interconnect.

Hive / Steem seemed really promising, I tried each for a couple years. They are a blockchain social media. It is somewhat like more of a blog than Facebook, but with following users, categories, and every upvote is a tip of the cryptocurrency and some people can make good loot posting stuff. Every post/comment requires a small crypto fee, so signing up is a little funky. There are free options, but a couple bucks worth of their coin helps get going faster. There are a ton of website and app interfaces to them, that look very different and change it from being youtube, to blog, to facebook mode in away. The upvote-tip strategy boosts posts (as does buying a boost on your own post), but that seems to push a viral new posts are king feel, that made > week old posts seem dead. Also, large files (images/video) aren't on the chain.

Memo Cash is cool. I've tried it a bit. It's a similar strategy to Hive/Steem, but feels closer to Twitter.

I've briefly tried ScuttleButt, a non-blockchian p2p social media. You are completely alone and you have to manually link of with people, unless you go to a "Pub Server" to meet and connect to people. Seems cool for messaging, but maybe more chat and socializing works out too.

Retroshare is an older heavily encrypted P2P social media. It seems cool for messaging and file sharing, but is has a ton of features like broadcast video, voice chat, e-mail-like message, chat lobby, forum, etc. It's totally a closed darknet and you pretty much have to exchange PGP keys with someone to talk to them.