API firmware development with cloud server, integration with Microcontroller

Copy-pasted bids will be rejected. We are working on a project where we have a printer(USB printer) and we want to make it wireless. So essentially we are looking to build a system that can be connected to the printer on the USB port which will do all the mods. We are open to suggestions. Operation: This system must show up as an air printer on phones and computers. the way it does for actual air printers. Once the user sends a print command to this air printer, the system must receive that and send that file to a server, AWS or anything else that can work for 1000 devices without an issue. Once the server receives the file, it must be able to make some changes to the file, mostly the pdf/image would be cropped and rescaled to a preset dimension. Once this is done, the server sends this cropped image/pdf back to the system and then the system can send this newly received print file to the printer via USB port. We need suggestions on using cost-effective parts as the total cost should be around 20 USD or less per unit of the system. I will suggest about the printers that can be used. We need to first choose an appropriate microprocessor/controller, whichever should be good enough for this. Can we get this done using a microcontroller, if yes can we choose a low-cost MCU so that we can have this as cheap as possible? I am an electronics engineer and I myself will design the PCB for this, but I need someone to assist with the software part of the project. Please reply with some possible solutions and if you have relevant experiences, share those as well. The key requirements are cost-effective solutions and the ability to have 1,000 or more such systems working together without an issue. We do not want to install any app on the phone, we want it to show up as an air printer on the phone so we can use it the way we use traditional air printers. Of course, there will be some initial setup and configuration and that is okay for the printers but we do not want to have any app installed on the devices. Kindly avoid copy pasting I will test the files/ ideas shared by you to verify it on a breadboard type of setup first, post which I will also get a PCB fabricated, of course, I first need suggestions on what to use. I will test your work on that PCB as well and once it works as expected, I will release the payment. Ensure to bid only if you are 100% confident that you can get this done. Reply with RCCAR In the start so I know you read this proposal throughout.