Store your files with ChainSafe Storage and retrieve them via Raspberry Pico. This tool will make it simple to upload your files locally, so you can free up your USB verify the service only ever stores the exact bytes you ask it to. I put to get a small list of providers to select. I plan to be grown this project to expand to more providers.
To use upload go to a raspberry pekoe with the required dependencies and just start using it as a USB/micro controller