Check the snapvolume config file(standard appstacks have one too)
and check, but I'm pretty sure most user profile stuff is removed. Look into what someone mentioned on your other post, you can create a custom config to export the files on logoff and reimport them on logon.
The appstack is read only and it does not contain any user data like APPV. Thing is these are physical paths and there is no isolation so Appvolumes will not be able to store any info that is whithin the c:\user of HCKU into an Appstack. So you are not doing anything wrong, it is just how it is build.
If these are just files you could try and copy them during logon with UEM. Or run an install every tiome a user logs in to install that functionality.
If you ask me, installing software into the user profile is just bad programming. Normally you would be able to get an administrative installer that puts data into the program files folders. If not you should be looking at workarounds.
You would need to deploy it outside of appvolumes. This will be tricky, because if you deploy via GPO for example, it may deploy at computer or user logon and UEM may not be ready in time for it.
Personally, I try to avoid these apps. I've never heard of "Google Chat" and everything that comes back is hangouts. I'm a big google user and was hoping this would be of interest to me.