From your message, sounds like you have 2 Roku devices but have lost both remotes. Unless by different model, you meant another branded streaming device.
If that is the case, yes... easiest method is to buy a new compatible Roku remote (walmart, target, best buy, etc. to setup the wireless networked Roku device or a universal Streaming remote.
If you still have the remote from your wired Roku device, maybe you can pair it to the wireless Roku device if compatible and get it set up on network, then use your app from there.
Not sure what kind of devices/models of device we are talking about here.