Roku reversed course on that. Back around 2018 when they launched RAF the thought was to make it available for all channel. The (likely) problem was most advertisers & buyers weren't interested in people watching small, niche channels as opposed to (examples) CBSNews, Tubi, Roku Channel etc. So after about a year they shut it down for small channels and said they'll select you if you're big enough.
If you're DP chances are you're too small, although I think 1 or 2 people posted that they were on RAF, I may be wrong on that, regardless I'm sure the viewers stats need to be quite high.
