Don’t know who exactly you are interested in, here are some random known accounts:

• the EU commission (other EU institutions as well): ec.social-network.europa.eu/@EUCommission
• gog games: mastodon.world/@goggames
• The New Stack: hachyderm.io/@TheNewStack
• Mozilla: mozilla.social/@mozilla
• Rust foundation: social.rust-lang.org/@rust
• Free Software Foundation: hostux.social/@fsf
• Electronic Frontier Foundation: mastodon.social/@eff
• Greta Thunberg: mastodon.nu/@gretathunberg

Regarding individuals, I’m following a bunch of software developpers. I’m mostly interested in topics, hence I prefer Lemmy by far.