No, you only have to make your proprietary compiled object files available. what lgpl requires is for the user to be able to update the LGPL parts - so Qt in this case and this does not need your code.

Source: https://www.gnu.org/licenses/gpl-faq.en.html#LGPLStaticVsDyn...

Is that just actual static linking, or is bundling everything in a directory okay?

Bundling a directory is fine if you're still dynamically linking.

Correct. As long a linking is dynamic, Qt doesn't care how/where the Qt libs are distributed. They typically recommend bundling for Windows and using system packages for Linux.