I mean, it seems almost too obvious, now that Twitter's done it, but Instagram is reportedly also testing out quick emoji reactions for direct messages in the app.
Instagram is working on Reactions for Direct Messages— Jane Manchun Wong (@wongmjane) January 30, 2020
Currently, “non-employees can only see the ❤️ reaction”
Facebook’s Tech Comms Manager @alexvoica confirmed this unreleased feature and this is “something they’ve been testing for a few days” pic.twitter.com/EzVWfA6Doo
As you can see in this tweet from reverse engineering expert Jane Manchun Wong, Instagram's new DM reactions are currently only available in test mode to internal employees. Non-employees, as noted, will only see the 'heart' response at this stage.
As with Twitter's recently launched DM reactions tools, given the availability of similar response functionality on other messaging platforms, it makes sense for Instagram to move in-step, tapping into habitual messaging behavior in order to facilitate more engagement. Instagram, it's worth noting, also already has a 'quick reactions' emoji response process for Stories.
It also makes some sense in terms of Facebook's broader vision of a fully-integrated messaging back-end, where users will be able to message each other across platforms. In that scenario, Facebook - which already provides reactions in Messenger - will need to facilitate the same functionality on each of its messaging surfaces. And yes, WhatsApp is reportedly working on the same.
As noted by Wong, Instagram has only begun full testing of the feature recently, so it could be a while before it's actually rolled out to users (though in a follow-up tweet, Wong does note that Instagram has been working on the option since October last year).
In terms of potential brand use, the functionality seems fairly limited, though recent research has shown that consumers do respond positively to brand emoji use.
Either way, it's another Instagram feature to look forward to in the near future.