You can type them in your posts and they will be parsed and made into t tags in the event.
But you can't build a feed off of them currently.
nostr:nprofile1qqswuyd9ml6qcxd92h6pleptfrcqucvvjy39vg4wx7mv9wm8kakyujgpypmhxue69uhkx6r0wf6hxtndd94k2erfd3nk2u3wvdhk6w35xs6z7qgwwaehxw309ahx7uewd3hkctcpypmhxue69uhkummnw3ezuetfde6kuer6wasku7nfvuh8xurpvdjj7a0nq40 Is Hashtag support a thing in Gossip? Like in Amethyst I can follow them
Discussion
Ah, I see. Yes the feed functionality is what I am looking for.