Can you elaborate on the client issues? We decided to go with WebAPI for universal access. Also, for public images, you can reference the endpoints directly in your HTML, so <img src="https://bitbox.co/files/1.png">
Now what you don't have, is a client software which allows any employee to use your storage system easy.
Only a WebAPI is not enough. I would even prefer any S3 open source self hosting solution over your solution and put a backup strategy behind it.