I can only tell you for Windows: Go to your documents. In there you will find a folder "Adobe". It includes basically everything you have customized.
For example on my machine the workspaces are in C:\Users\<username>\Documents\Adobe\Premiere Pro\<PPro version>\Profile-<username>\Layouts
The keyboard settings are in C:\Users\<username>\Documents\Adobe\Premiere Pro\<PPro version>\Profile-<username>\Win ... and so on. There are plenty of files and subfolders in that Adobe folder, so you gotta do some digging. But it's all there.
In case you are on a Mac simply look for a file called "UserWorkspace.xml" in Finder. That should lead you to the folders where all your Adobe stuff is.
I have found the files buy cannot see which is which they all have the same name "UserWorkspace". The issue comes from the fact that I am trying to use Beta version of the Premier Pro & Media Encoder on my M1 MacBook Air but it hasn't pulled accross the presets and Workspaces from the current version (like when you upgrade) it's very frustrating.
I now have stuff in the normal veriosn I cant access on the beta and have created new ones in the beta version I cannot see or use in the normal verions. It's very frustraing.
If anyone can tell me howe to move things accross in a sensible way. I have tried to use online sync but it it doesn't work on the beta.
The other thing is that I would like to use the same settings on more than one Adobe Creative account so being able to export/import these things would be extremely useful.