Programmatically uploading files to WordPress is really just the same as uploading files from any source location to a destination.
That is to say, there are a number of PHP functions all of which make it pretty easy to deal with file-level operations, grabbing files from one location, and moving them to the next.
And yes, there are some nuances that can come with PHP’s configuration such that you may not be able to write to certain directories, perform certain options via HTTP, and so on. All of these can be managed by either changing up the configuration or by changing the way in which files are handled by the code.
One thing that WordPress offers that manual uploads don’t manage is adding files – specifically media types – to the Media Library after uploading a file. This is relatively easy to do given media_sideload_image.
But let’s say the situation is a little more complex.
