I am watching DVDs on a 1080p projector to the large wall of my living room. It is a 10y old cheap aliexpress one so it is not the sharpest you can get and it actually makes the DVD enjoyable as it smoothen a bit the whole thing. I don't really know what is at play but I can only say it seems to blur the image in a pleasant "optical way", not like if I was applying a gaussian blur and was watching it on an high dpi screen.

Makes perfect sense; old CRT TVs had the same kind of effect in making low resolutions bearable. (If you think DVD is bad, you'd have loved long-play VHS at around 230p...)