I use AMZ-Image with Gutenberg. It works well for placing images from Amazon that aren't the default image and you can place different sized images. You have to have access to the Amazon API to use it. Other than that, there are no other restrictions. It is a simple app that works as described. The plugin doesn't affect page speed much. I still have page scores of 90 or above for mobile and desktop on Google page speed.

The only little quirks I have found so far are as follows:

When you place an image in Gutenberg, it always places the image at the bottom of your post no matter where you are currently trying to add a block. You have to then copy the block and paste it where you actually want it to go.

When selecting images, once you select an image other than the default first image, you have to close out the selection box and search again if you decide you want to use the default first image. It won't be selectable after you click on any other image.

These don't really detract from the functionality of the app but they are small annoyances.