It was confirmed today by Mark Zuckerberg via a post on Threads that a keyword search feature will be coming to the app soon. This was quickly followed with a post by Instagram Head, Adam Mosseri, who confirmed this and added that a test is underway in Australia and New Zealand.
Testing of the keyword search feature starts today and will be rolling out to other English-speaking regions soon. There was no specific timeframe provided for the rollout in stable but Mosseri did add that they are also working on adding more languages and requested feedback from those who are already testing the feature. This is pretty significant considering that, as it stands, the only thing you can search for in the app are other accounts.
However, it appears that Zuck, Mosseri, and the Threads team are not sitting on their laurels and are instead working diligently to bring most of these features to the platform as soon as humanly possible. With the mostly highly requested features already implemented or on the way (Web client, Following feed, Keyword search), the team can now move on to working on the implementation of Direct messages, hashtags, and other features that the competition already offers.