As an image is binary file, to upload a binary file using parameter in bubble.io you have to swtich the body type to FORM then add a parameter and it will give you option file on left of private option check it and then you can send binary file.

there are option to add thumb to product using url. if you tell me you actual use case i can help you sir.

tell me what you want to achive, how you are trying to achive and i will help you.