They are part of the "smolnet" if I am using that terminology correctly (including the Gemini protocol https://geminiprotocol.net/). Other sites I will browse or lurk include, Lemmy (join-lemmy.org) Reddit alternative, Mastodon, BlueSky, SDF.org 's IRC, Matrix, some Telegram communities, lobste.rs, HN and ideally IRL at 2600 meetings https://www.2600.com/meetings, conferences, Linux User Groups (LUGs) etc. I still browse Reddit, LinkedIn, Facebook and Instagram occasionally. For 1:1 communication I most often use SMS texting/iMessage, regular phone calls, FaceTime video, and Facebook Messenger to talk to other American friends, family, etc. To talk with technical people and folks abroad, I'll use email, Telegram, Viber, Skype, Signal, WhatsApp, and rarely Instagram Messenger, all of which I need to get better at staying on top of.
If you take the definition of tilde from tilde.verse {tildes are pubnixes in the spirit of tilde.club, which was created in 2014 by paul ford} then it should be relatively straightforward to see why that address is related.