How can I provide my own conversions (already created file) at creation time?

[vesper8]

I'm dealing with race conditions because I'm uploading the image straight to AWS S3, then my client notifies my Laravel backend that the image has been uploaded, then I add the image which is already at this point stored on S3, then non-queued conversions occur and thumbnails are returned to the client. All of this seems to run into race conditions and sometimes the thumbnails, despited being non-queued, are not created quickly enough and I have to add an artificial sleep()

My client code is capable of generating the thumbnails so that media-library doesn't have to do it

I would like to be able to use a withConversion($name, $conversionPath) where I could provide media-library a path to an already-created conversion at the time I am adding the image to media-library

Is it possible to achieve this at the moment by any chance?