Extending asset filename validation on Classic UI



I have a requirement to validate filenames on Classic UI uploads. This is a very similar requirement as this other question, but for Classic UI - Extending File Name Validation in AEM Assets

I tried to find the equivalent javascript file to overlay but it looks like for Classic UI the asset upload process is vastly different. There also don't seem to be any OOTB configurations for asset uploads other than MIME type restrictions through OSGi.