I am in the North of Ireland, technically the UK. Why is discovery plus not a channel on the TV options. I understand you can stream from your phone... And I can do that, but it does freeze as all streams do and I'd much rather it was a provided service. I can also hdmi my laptop but what is the point in paying for a smart TV then. Every other smart device seems to provide these apps. It is August 2021 and this question seems to have been asked quite frequently this year, warranting demand.
Roku themselves does not create channels for other providers. Discovery has to make a channel for Roku devices. And then, they have to make it available in a specific geographic area.
In this case, there is a Discovery+ channel for Roku devices. But if it's not in your device's channel store, that means Discovery hasn't made it available in your country. You have to ask Discovery to change that. Roku is not permitted to alter the geographical settings for 3rd party channels.