In addition to being able to upload product images on the add/edit Product view in the Shop app, you can also upload images through the Media Manager and then edit a given product or product variant to select the upload image. This is particularly useful if you wish to upload a series of images at once and then associated them with their given products.
Prior to using the Media Manager to upload a product image or images, you should confirm which storage folder is used by the Shop app for product images. By default, the folder is /storage/images. This can be confirmed in the Configuration of the Shop app. For more details, see Setting the storage folder for Product Images.
After confirming the storage folder, use the Media Manager to upload the image or images. For details, see Viewing, uploading, and managing images and documents in the Media Manager.