Can you download custom iPhone vibrations? I know how to create vibrations on the phone itself, but I'm wondering if there is a way to upload to a computer, download from a computer, or even create on a computer.

I ask because I'd like a way to save and share vibrations (like you can with ring and text tones). And if there is a way to create them, that would be great. Because, let's be honest, you have a great deal more control over timing if you can use a computer.
No. There is no way to share the ones you created manually on your iOS device, and you can't import them.

I don't think they are even synced across devices.