Roku isn't sold or supported there through any official channels. How that impacts Disney+ is as follows.
Many app developers, including Disney, will not support or offer their app in a region where Roku itself is not supported. Some developers, such as Netflix, do support practically everywhere, but most do not. Disney chose to not support a Roku app in your region. Again, that was a decision Disney made, not Roku. Should Disney update the app to work in your region, it will work and be available in the Channel Store. Unless and until they do, it will be be available there.
Keep in mind this has nothing to do with Disney+ or any other service being available there. Each platform is different.
Roku Community Streaming Expert
Note: I am not a Roku employee.
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