PlayOnRoku API - custom Headers, further documentation?

I've read just about everything I can find on google about any known usage of what appears to be the "PlayOnRoku" channel (15985). It's been mentioned a few times in scattered parts of the web that the URL to an mp4 or hls video can be posted to a roku for streaming via this endpoint:

http://${ROKU_IP}:8060/input/15985?t=v&u=${VIDEO_URL}&videoName=${VIDEO_NAME}&videoFormat=${VIDEO_FORMAT} 

Here are a few links to forum posts or blog/github issues mentioning this API:

I have found that this works, but there are cases where I would like to have control over what headers are sent to the "VIDEO_URL". Is there a way to provide custom headers via HTTP request that the roku channel will attach to any requests sent to the video-server?

A much larger question I have is whether there is any public place that documents this usage. I have been unable to find any official information on what parameters are exposed for controlling this channel, and there is clearly some interest in the community to make use of it, so I am confused why it is not more accessible. I am wondering if this is intentional. Is public usage of this API deprecated?

Tags (1)
Community is Temporarily in Read-Only Mode!

We’re upgrading Roku Community to bring you a faster, more mobile-friendly experience. You may notice limited functionality or read-only access during this time. You will not be able to log in or post new comments or kudos during this time. Read more here.

Planned Downtime:
Community will be unavailable for up to 24–48 hours during the upgrade window during the week of May 12 and you may notice reduced functionality. In the meantime, for additional assistance, visit our Support Site.

Thanks for your patience — we’re excited to share what’s next!