Can you publish this as a package via https://openupm.com/?
Instructions can be found here:
https://openupm.com/docs/adding-upm-package.html#upm-package-criteria
Currently, a package with this name already exists, but it looks like it's a fork with some modifications.
https://openupm.com/packages/com.bunny83.simplejson/
Also, unfortunately, that specific bundle doesn't even work :(