Where to go for free 'KeyValue' DB storage?

Anyone have any recommendations RE the AWS ecosystem for image storage? I've been looking into cloud storage NoSQL services like AWS, to create a NoSQL db to hold fake 'inventory' and 'stock' images of a fake car website that I'm coding. I'd like to integrate my own metadata objects around these free, publicly-sourced images (.webp ), just to ensure maximum searchability on my site and in general. So I'm looking at using a 'Document Store' NoSQL db, like MongoDB, and feeding it .json objects that have my custom metadata along with the image binary. This can be done for free with AWS's DynamoDB, however, that platform places a 400kb cap on images, which is like, meh. To help resolve this 400kb cap issue, AWS S3 is offered, a separate key-value db for the raw image binary that I'd reference in the DynamoDB json instead. Now, Amazon S3 is not 'always'' unpaid, like DynamoDB is, so I looked at Mongo, but none of Mongo is free either. Does anyone have any recommendations for me, if I want to avoid having to set up a subscription to hold this binary image data, or else another way to approach this? Would the only "unpaid" be to just run the key-value database off of my own server or something? Or should I maybe be taking a totally different approach to this?