Even 20x50's with good glass are difficult to use. 20x is difficult to handhold for a steady view and 50/20 = 2.5mm for an exit pupil, not a lot of light. Many years ago when I had a need for a big lens, I picked up a set of 15x80 binoculars. It came with a tripod mount to hold it steady and the 5mm exit pupil was much brighter than even the best 20x50 binoc's. The difference of course was $$ -- those 15x80's came with a serious price-tag. Magnifying power is a good selling point, but power doesn't mean much if the image is bouncing around or is too dim to make out detail.

I have two pair of 8x30's (Nikon & Steiner) and they work well in bright sun; these days with eyes that have many more years on them, my daytime binoculars are 7x35 Nikons (5mm exit pupil) which work dawn-dusk. For the time between dusk and dawn you need to be looking for a 7mm exit pupil which is the most your eye can use, 7x50 binoculars with good glass are the standard.

Back to the subject of monoculars -- the monoculars small enough to drop in your pocket will generally have small objectives lenses and that makes for a dim image -- 8x20, 8x25. I suppose those are okay for daylight spotting, the objective being to identify a landmark for navigation and such. Birdwatching or other extended viewing, needs better glass and needs to provide a steady, bright image. I don't see that happening with a small pocket monocular.
$.02, ymmv