It seems to me they they just use the plugins that anyone can use for Lumberyard. Speedtree for example.Internal tools for CIG only (like Fdev with Cobra).
"dependent on the continued funding" like any other company. No funding, no company.
I guess they develop their tools since the ILLFONIC debacle (2015 ?). If so, 6 years of development on a game engine is not negligible.
Q. Can I take Lumberyard and make my own game engine and distribute it?
No. While you may maintain an internal version of Lumberyard that you have modified, you may not use Lumberyard to distribute your own game engine, to make improvements to another game engine, or otherwise compete with Lumberyard.
However, you may distribute your own fork of Lumberyard via the Lumberyard Repository on GitHub, as long as you comply with the requirements of our terms, and include a copy of our license notice in your fork. Users who use your fork must agree to the AWS Customer Agreement and the Lumberyard Service Terms, and their use of your fork is governed by those terms.