@BeAware@rikiti9 no, Mastodon doesn't have the concept of following a topic.
It's up to the software implementor to do something like that.
NodeBB, for example, does allow you to subscribe to a topic. My replying here automatically subscribed me to the topic so future responses (even if I'm not mentioned), will notify me.
@julian
Interesting. Does #NodeBB implement #ActivityPub natively as its core mechanism or is there a plugin to allow a NodeBB server to be federated? @BeAware
@rikiti9 I am building ActivityPub integration into the next major version of NodeBB. It is still in development but moving towards an alpha release soon 🙂