There are medium format projectors too. I have a few, and they are spectacular.Of course we all have differing needs and desires. So I;m not knocking projection. It;s a great way to show but I also shoot medium and large format. What then? Also, convenience and shareability are real plusses. I never used a digital laser projector so I can't comment on that. But TV as well as cellphone, and monitors emit light brightening the picture unlike reflected displays from projection. Light intensity is more and contrast is as well depending on how you adjust the displays. There are settings on TV's where you can switch to predetermined contrast and other color and light settings with one click for a slide show. I don't bother because the show is bright and contrasty enough from my standard TV viewing. I will say that a good monitor displays the shows sharper although with smaller screen size than a 75" TV. With new 8K tv I might have to start editing for that size although you probably won't notice a difference to 4K.
Crossfades (transitions) are standard when I do my video slide shows. Did you look at any of mine on YouTube linked below. They all have trasnitions and fades and there are dozens of different types that can make the show fun to watch. See picture below of Adobe Premiere Elements video program that was part of a slide show I did for my grandson's first birthday. Note all the differing transitions available on the right.
Large format slide lends itself to direct viewing. But projectors for that exist too.
Projection on scotchbrite/3M RR screens when you sit within a few degrees, the image is as bright as any screen (though also a tiny bit grainy, but not worse than pixels).
Slide can also be viewed in an enlarged view slide viewer (binocular style or enlarger) which can look fantastic too.
There the limit is your backlight and how much magnification you can get.
But if you are not too greedy with screen size regular projection is plenty bright.
I can do a “slide show” any day within a few minutes with my scanned photos. I really don’t see that as the same thing at all.
Slide viewed directly and not through a scanners interpretation is something very magical all its own.