Third-party open source licenses + request for LGPL sources

Under Help > Software Licenses is a huge list of 3rd party components and licenses. If we distribute a packaged binary, are the components in the packaged binary a subset or superset of that list? Are there any components on that list that are not included when we package a binary?

Also, for the LGPL 2/2.1 components:

 Qt GUI Toolkit, cross-platform application and UI framework | GNU Lesser General Public License, Version 2.1
 7-Zip Command line version | GNU Library General Public License v.2 or later
 Lame | LGPL 2.1
 libwebsockets - small server side websockets and web server implementation | GNU Library General Public License (LGPL) 2.1, with the following exceptions
 websockify.js.  A JavaScript implementation of the websockify WebSocket-to-TCP bridge/proxy | Licensed under LGPL-3, see http://github.com/kanaka/websockify for more info

... where can we get a copy of the source used of those libraries as used in Unity 2018.3.3f1, so that we, too, if needed, can provide the source to our licensees (i.e. our end users)?

And is it true that Unity is only linking to these LGPL libraries? (I assume so, just checking)