Currently, I start Zwift on the PC, watch Zwift on the TV, and never touch the keyboard/mouse while I’m riding. I can see it can be useful to change the camera view and perhaps do a shout out to someone who passes me. I don’t really want a keyboard draped over my handle bars, nor do I want to lean over and pick it up each time. What does everyone use today? A smaller keyboard with integrated track ball? a side table with the keyboard on it? nothing?
Ideally, Zwift wants you using their mobile app, I suppose with some sort of mount on your handlebars. They do sell handheld-sized bluetooth keyboards (designed for phones, but work on PC). I don’t think they are worth buying just for Zwift, but may work if you already have one.
What I do most of the time is set up a table to one side of my bike and place my keyboard there. This way I can quickly press space if I need to, or set the keyboard on my handlebars if I need to type a message. If you don’t have a table, you can really use almost anything: crates, buckets, cardboard boxes, speaker stands, etc. I also play in my garage so I have lots of resources to choose from.