1.4X and 2.0X teleconverters are a mixed bag. There are lenses that are designed to use a specific TC and those are fantastic. And there are generic equivalents that can be tried on most lenses. And for the most part, they don't work so good. I don't own any good lenses with their matching TC as I don't have the budget for them. I do have some generic TCs and I find that I don't get very good results.

CIZ with a decent lens should beat the generic TC's. Plus you don't have to deal with loss of light.

I do have a couple TC's that screw onto the front of the lens. I do find that they work better than the TC's that go between the camera and lens. But they are really heavy. If the camera has image stabilization, the camera does not know about the extra focal length and can miscalculate the amount of sensor movement to use. Plus, all the extra mass on the end of the lens may cause the focus motor to struggle. One of these kind that I find does work well is the Olympus T-CON17 which provides 1.7X. It works best if used with a steady tripod with perhaps manual focusing. These types of TC's were once popular but have fallen out of favor. They were once very expensive and now they are a fraction of the original price. I only use them for experimenting.

CIZ is as good as it gets without doing post processing. Post processing will beat it. Especially if RAW is used. But if you're not into post processing, then it doesn't matter. Just enjoy your CIZ.