I assume this page describes what changed since 1.0:
Since the original release 1.0 of the WebAssembly specification, a number of proposals for extensions have been integrated. The following sections provide an overview of what has changed.
No garbage collection integration yet? Or is it done as a separate work?
It looks like garbage collection is at the 'proposal' stage, one step before it would start to be implemented.
"During this phase:
"One or more implementations proceed on prototyping the feature to the point that a comprehensive set of tests can be added.
"A test suite is added. These tests need not pass the reference interpreter at this point, but should pass on some implementation."
https://github.com/WebAssembly/meetings/blob/main/process/ph...
Here's the proposal:
https://github.com/WebAssembly/gc
And you can see it's being actively worked on: