I'm torn on my opinions towards a third prequel. I didn't really like the direction they went with in Covenant, though I loved Prometheus (I know that automatically means some people will disregard my opinion because of my taste, but also my favourite version is the fanedited workprint and/or chaos edition, so make of that what you will).
I didn't like the concept that David created the alien, so I'm not sure I'd want to see a film that leant even further in that direction. I also disliked the changes to the alien biology, and how easily (comparatively) they were disposed of (though I know that can be put down to being an early model, so to speak).
At the same time, it does feel like the second part of a trilogy, and that we're missing the end of the story. It feels unfinished, and I can't help but think that unless the TV show connects to it, somehow, it will remain unfinished.