I have an M3U8 playlist that consists of around 70 individual links to different HLS live streams. I am able to use that playlist on Plex Media Server - via a modified version of IPTV and it works flawlessly. The channel shows each link and I can select ANY link and it will play on my Roku via IPTV on Plex.
Therefore we can assume that this type of playlist is within the spec of M3U8?
I realise there will be coding to do, to allow the same to be done directly via Roku... not everyone has or wants a Plex server - that is why I am attempting to build a Roku app that can "read" my playlist and then play the chosen link.