Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
This is a question that should be directed to Apple. They are the ones that create, supply, and maintain their Roku channel app. Roku just provides the platform on which the Apple app runs.
The more models with differing capabilities a channel supplier tries to support, the more complex their app becomes and the more difficult it is to maintain, beta test, etc. Only Apple know why they chose to support the models they did.
Roku Streaming Stick +, 3810X, Ser YH0059427035, wifi - Samsung UN55ES6100
Roku Streaming Stick, 3600X, Ser 5S56D8240827, wifi - JVC EM37T