@sleepstimulant you're definitely on the right track using hashtags. That's one of the best ways to find stuff people are really talking about ime.
There are also "groups" on Mastodon via the gup.pe instance. You basically tag a topic & if the group exists, the group account/"page" will automatically boost any post its tagged in. If the group doesn't exist, it will be created when you tag it. :) Kind of stressful since like what if I use a wrong spelling or something & create a new group LOL 🤷