The #welcome channel in the Pants community Slack (https://pantsbuild.slack.com) is the best place to discover what large companies are using Pants 2, including Fortune 500 companies.
I'm preparing to launch a series of user interviews on our blog (https://blog.pantsbuild.org/) in coming weeks. Those in-depth conversations explore things like how the Pants 2 adoption process has gone, benefits their team is experiencing on the ground, pragmatic comparisons with alternate solutions the company has used or evaluated, etc.