You will have to have a physical remote. However, it doesn't have to be a Roku brand remote. All Roku TVs support an IR remote, and universal IR remotes can be found in many local stores for under $20. Just make sure they list Roku as a supported device.
I've also found my Vizio TV remote will control my Sharp Roku TV, although I have no idea if that's specific to the Sharp or applicable to all Roku TVs. If you do find a remote on hand that works, you'll likely have to play with the buttons to see which does what. 
Dan
Roku Community Streaming Expert
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