Chris has given the OP some great advice on how to get more from their current kit. Incorporating that advice in their shooting should pay dividends. It will also help to develop a skill set and mental approach to wildlife photography that can be applied to any equipment upgrade the OP makes.
I'll offer two additional pieces of advice. Looking at the first set of images shared in the top post, they appear to be straight-out-of-camera JPEGs. If that's the case, I'd recommend shooting raw and doing the image processing out-of-camera in a photo editing app. The reason is that sharpening and noise reduction are applied globally in-camera. Sharpening is applied to the sky, water and out-of-focus areas that don't need it. Noise reduction is applied to the subject and that softens detail. Shooting raw and processing your images in an app will allow you to maximize the quality of your images.
The second piece of advice I'll offer is to position your camera & lens at eye level with the subject. When photographing geese on a pond, that means getting the lens just above water level. Sometimes, a change in perspective is all that's needed to elevate and OK photo into something special.
I have learned SO much in the past few days from everyone's feedback, so again thank you to everyone who commented.
RE to Bill Ferris, what an amazing tip, even w/ those SOOC JPEG's I had never thought in my 'editing workflow' to manually only sharpen the subject via mask. That helps even the JPEGs significantly. And yes correct again, they are JPEG's SOOC, I'll try raw + JPEG next time as well.
Some realizations and things I've learned below. Maybe it might help someone in the future:
I have been shooting my 7D's in Spot AF mode, I read up on the different types, there is Spot which takes a extremely small portion (few 'pixels') of the image / viewfinder to grab focus. It looks like a box, within a box. I learned this is good for say shooting through fences or brush, but can make the camera struggle if I try focusing on a dark part of a goose for example. Switching to normal single point AF seems to be more better, and should hopefully let the camera see more of the scene and get (again hopefully / maybe) a more consistent focus.
Next, the rope test shots from above are A) Yes John Crowe is correct I should have posted the same settings (or as close as I could) w/ the T7, but B) I didn't know the 7D has some sort of issue w/ shooting in live view with "live focus" see the images below, but there is a substantial degradation in quality between live view and viewfinder shooting, with the exact same settings (or very nearly). So much so both my 7D's exhibited this behavior, but my T7 and 50D did not. Switching the 7D's to "Quick Mode" focusing helped, but still wasn't as good as viewfinder, you can see below. So those from the 7D's above with the rope I'd just toss, if I shot them with the viewfinder I imagine they would be sharper.
Next was back to Chris R-UK's point. Looking through the exif data of all the duck/goose photos I took that day, the recorded focusing distance was consistently 70-80M, or well over 100ft away. Yet I'm expecting (my fault for expectations) the same level of detail with a bird filling the frame at say 20M or so. Which, is actually impressive I got some reasonably sharp shots on a nearly 20 year old camera, that far away, with heat haze and a sloppy technique

(For example in the original post, the duck photos were at about 70M focus distance.
The best sharpest photos of the day were shot at 20M focus distance away or about 65ft in very good light.
Last, I also realized I shot every image at -2/3stop to prevent peaking, but I realize now that may also contribute to noise showing up even more than just a normal 0 exposure.
On to the results below. I did some substantial testing, because I wanted to see if the highest iso really did reduce actual sharpness. I had heard that technically it won't but the precieved sharpness declines as noise gets added, but with the conflicting rope shots, I wanted to just see.
Once I figured out the live view issue, I overall wasn't that surprised. The iso 6400 shots were still sharp, yes quite noisy. I had heard over exposing via lower shutter speeds by say 1/3 stop can help the camera gather more light and reduce noise a bit, I didn't find it to be the case, it seemed to brighten the image up and exacerbate the noise weirdly.
Regarding upgrading / differences between a higher resolution sensor:
There is a noise difference between the 7D & T7 at max iso and 3200, the difference follows each other to about iso 400-800 range, where they seem on par with one another.
Correct to everyone who said it would have less noise, it does, but I was more interested in sharpness, which like Chris R-UK hinted, and I saw kind of in my last post, it's not a substantial gain jumping up to 24MP, with the caveat it's a quite old processor, sensor, etc. Yes I'm sure a 90D / mirrorless would be even better, but the noise just doesn't bother me super much, especially with the de-noise tools available.
All shots below:
Locked down on tripod
AV-Same settings with a slight shutter speed diff here or there but nothing huge
Same ISO's
Live view for T7 and 2-sec timer
Viewfinder + 2-sec timer via wireless remote for 7D
You'll probably note it seems the T7 is closer to the chart. I'm not 100% what is causing this, but the tripod certainly did not move.

Live view issues / Live view focusing issue

Exact shot I just turned live view off

7D Max ISO; no in camera noise reduction

T7 max iso; no in camera noise reduction
I posted for help, as most of the pictures I took where somewhat similar to the first post, but the trip wasn't a total wash. Looking back, I think the photo below summarizes everything I've learned (getting closer, better technique, better lighting, lower expectations) except the AF focus point and live view stuff.
I just wish I could get these more consistently

I think everyone's input will help me do that!
Thanks again to everyone who commented and posted, I value it, I am looking forward to your thoughts or tips once more.
Roughly an 80% crop of this image. I'm feeling confident I could get this level of sharpness even at ISO 800 possibly even 1600 with proper techniques!
