Hi Emerson,
The Polymer image upload works based on following api's
/p/fileupload/maximumFileSizeForUpload - Get request to retrieve the max file size configured in web property
/p/fileupload/validImageExtensions - Get request to retrieve the include and exclude file extension configured in web property
/p/fileupload/uploadimage - Post Request to upload the image to the server
To understand in details about this you can check the <triplat-image> web component all protected methods (but do check _doUploadFile for sure)
I am not sure whether @tririga/tririga-react-components has api or component to upload the file, but it does have one for downloading the image. But you can use the above api's and create a component or api for uploading image.