Not a bad idea, but a major source of revenue for Roku is via selling advertising "space" by hosting internet-based streaming channels - they make nothing on OTA broadcast/antenna TV, so most certainly aren't interested in facilitating its use any more than they have to. In fact, I'm quite sure they'd prefer we don't watch broadcast/antenna TV at all, being it's significant viewing competition for their revenue-generating streaming channels.
Just you wait... In the future, don't be at all surprised if Roku pulls numerous OS "tweaks" that make it more cumbersome to access and watch OTA, broadcast TV (they've done it before). Such is the typical modern-day, corporate standard MO of nudging the ethical boundaries of free-for-all money grabbing, wherever and whenever they can - users be d@mned. 😠
And the antenna TV channels are all bunched together at the head of the "All channels" list, anyway (channels 1 - 69), so I can't see much reason to further clutter up the categories list with a dedicated "Antenna TV" category. Just "Favorite" an antenna/OTA station, and Bam! - you're there, via "Favorites", just the same. Well... sort of...
JMHO, anyhow...
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