I believe Roku has decided to focus on Voice support rather than keyboard support. With their Voice remotes, you can basically speak one letter at a time now to enter passwords as well as perform full searches.
Like you, I do prefer keyboards for searching, but not really practical or necessary for the Roku device. It should be easy enough to implement though. Only current method of using keyboard search (at least easily) is through the Roku remote app available in the Play/Apple Store.
There were some online 3rd party Roku apps that connected to the :8060 port so you could use your laptop, but pretty much limited to searching content. (and in certain channels/apps - not entire platform). Has been awhile since I have used those and I remember them not even being actively supported and developed even when I was using them. These were really just projects that eventually were abandoned.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
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