I’ve been pretty satisfied with my method: Grab a point in the middle of the tone curve and drag it up a bit. This way whites and blacks will stay the same, but everything in between gets a little brighter.

I also make sure that I have some amount of actual white and black in the histogram (except if it doesn’t make any sense in the image)

That’s what I was thinking as well. The pictures aren’t bad, but look like any decent photographer worth their money should be able to capture them.

Exactly the viewfinder is not the problem.

I think it’s just OPs perception of their vision, it really depends on how much of your peripheral vision you notice, and expect to be included in a “normal” fov. Also your eye constantly darts around in a scene and assembles the image as you perceive it, so it doesn’t actually make much sense to compare to focal lengths of camera lenses.

Just shoot with whatever lens you like.