UL binoculars

Minolta (later Konica-Minolta) had a couple of those . (6x and 8x I think)
Don't remember the weight but were OK for the size
(similar, not the same)

Clamshell-style "opera" binoculars have been made for a long time, but heavier with lots for glass and metal and typically 4x. These aren't "fine" optics by any means, but I thought they were interesting in an UL way.

Opera glasses typically use Galilean optics, that is 2 lenses no prisms ,3x magnification, mostly a fashion accessory
These types do have a prism and a much more usable magnification.
(I sold some of those Minolta to opera goers)

These were 4.2 oz

Great for star gazing and often quality affordable options for 1-2 oz. Brunton makes a few, as well as Bushnell and others.

The obvious advantage to binoculars is in 3-D viewing. Depth perception can be critical, particularly in boating.

Optics aren't as necessary for hiking and lean to the gadget/toy side and unneeded weight. They can lend a lot of enjoyment to wildlife as well as astronomy. I could make a weak case for them being an aid to land navigation.

Personal preference but for one I don't like monoculars.
As well as the 3d viewing bit (sense of depth) I simply find it difficult to find the subject quickly with monoculars as well as holding them steady.
However I usually had in stock the largest selection of monoculars in town…(that is 3 or 4 compared to 40-100 binos)