How to Have Two Settings Bundles in Catalyst App

Create two folders, one named iOS, one named MacOS. Drag your existing Settings.bundle into the iOS folder. The bundle is in the folder when the blue underline appears under the folder. My XCode is broken. To get the "new folder" item to show up on the context menu, I had to select the existing Settings.bundle. This put both new folders in the bundle. I dragged them out.

Select your MacOS folder. Use the context menu to add a "new file". Select Settings.bundle. You need to scroll down to find it.

Delete the example entries in the plist. Customize. You can copy and paste entries from the iOS plist.

Select your project page. Select your target. Select "Build Phases". Expand "Copy Bundle Resources". Find your original Settings.bundle in the list and delete it with the minus button. Use the plus button to add your two bundles. For each, select the appropriate target (MacOS/iOS) in the target column. The second time you select the plus button, it will not show you the other bundle. I assume XCode doesn't think you need a second one. Select "Add other" to navigate the filesystem and find your second bundle.