What I imagined was a group (align to parent) with an image uploader in the back (full width/full height) and your logo in the front positioned in the corner.
You upload an image and use a plugin to transform the group into an image (there are a few plugins for it).
So what you can do is use an html element, and put in the html image code for your image. Then you can run the image through imgix which we have access to natively through bubble. Imgix allows for the addition of a watermark.
I’m not at my computer, so I can’t give you a perfect example, but this should get you there if you want to do the legwork to figure it out on the forum.
What I mean is that if you display the image in the page (I tried with the image element) imgix transformations are applied because bubble actually uses the image url as path for another endpoint. If you try to apply the imgix parameters in a workflow the resulting url is different and the transformations are not applied. Of course I am talking about images stored in bubble in both cases.