Copying Entire Animation Rig To Another Character?

INTRODUCTORY CONTEXT:
I have been following the 2019 SIGGRAPH Unity Animation Workshop Tutorials using the project from Github and the included Instructional PDF.

Working within the included project everything is ok (because it's using its own outdated version of Animation Rigging Package). The problems arise for me when attempting to reproduce the workshop in a modern project using an up to date preview version of the Animation Rigging Package.

Using the Animation Rigging Package, is it possible to build a complete rig by hand for a humanoid character ( for the purpose of implementing IK and hand animations ) and copy/paste it onto a second humanoid character?

I would like to know:

1. Can a fully built animation rig be applied to an unrigged character for the purpose of rigging the second character?
2. If not, must each character be rigged by hand when using Animation Rigging package?

The 2019 Siggraph Animation Rigging Workshop mentions using The Prefab System for moving Rig Regions between skeletons - however...

Animation Rigging Menu > Utilities > Mirror Transforms appears to be moved or deprecated. When attempting to reproduce the results of the workshop via the guide PDF I can only get to the point of saving a Rig Region Prefab. I cannot complete the very next step because the latest version of Animation Rigging Package no longer contains 'Utilities' in the package menu. Has this been moved? If so, where to?