They simply might not be available through Roku..unless processed through that media browser server thing—which sounds like a connected computer. And that is a service-specific thing.
I don’t use Roku....so I cannot help beyond that.
That said, have you considered mirroring your laptop to your TV. It “might” be possible through a Bluetooth or source connection. I can do it with my laptop...but the quality is not great.
It is, of course, a whole other balywick that might require some hands on.
Got the pluto app on roku to switch from m live tv to on demand! Now if I can just get oann!