A custom module must make changes to the schema following each setup:upgraderun. This must be done after all other module's schema updates have been applied.
How is this accomplished?

How can you access the select query of a collection?

A module declares the route:

What is the layout handle of the storefront path /custom/feature/?

You are adding a new entry to the backend menu that appears after
Marketing > SEO & Search > Site Map
You see the existing site map menu item is declared by the node:

What two actions do you take to configure the new menu entry location? (Choose two.)

There are two different configurable products which both share one variation. The shared variation is represented by the same simple product.
A customer added both configurables to the cart with the same selected variation?
How will they be displayed?