Reactions are not included. It‘s a coincidence that they show up on devices due to the old SMS reaction text parsing features both sides (iOS / Android) added to their apps years ago.So after a day of RCS it brings the most wanted features like typing indicators, read receipts, higher quality photo/video, and reactions.
But it's still missing basics like group read receipts and typing indicators in group chats.
I'll still dump whatsapp for it to consolidate into 1 messaging app, but it's still definitely inferior to messaging apps and imessage.
Reactions are part of UP 2.7, which Apple has yet to implement (they are on 2.4 from 2019).