I realize that gear is irrelevant and that a real photographer can take Net Geo quality pictures with a disposable camera but. (For those who don't get it right off this statement is made in jest, tongue in cheek, sarcastically)
I'm not nearly that talented so I need a " gear edge", when I choose to afford it.

Having cleared that up

Lately I find myself thinking of a new to me lens to fill the gap between my 18-55 ef-s (kit lens) and my 150-600 Tamron G2 for use on my Canon 7dii.

First question, or clarification. The 18-55 ef-s 3.5-5.6 II is a kit lens that was supplied with a crop sensor Canon Rebel T3i.
It is my understanding that the stated focal range of 18-55 has already been "adjusted" to account for the 1.6 crop factor.
Am I correct in understanding that this 18-55, IF mounted on a ff body, would produce results similar to a 12- 35mm lens?

My 150-500 Tamron lens mounted on my 7dii has an effective focal length of 240-960mm due to the 1.6 crop factor.

I'm leaning towards filling the void between 55mm and 240 mm.
My first thought is that I shop for a 70-200 but that actually would only partly fill the gap because the 70-200 ends up a 112-320mm

The 70-200 or a 28-300 would probibly be a good step in the right direction, especially for close work with hummingbirds or action shooting of dolphins.

Yes it's my money and my decision.

However I thought it would be interesting to ask the UHH group for thoughts and suggestions to fill my gap.