Yes. I don't see a large scenario where a company isn't already using G-Suite or Office 365 and the higher tiers include all the compliance and management features. Usually if they need more customization then they use OneLogin or Okta on top, or build their own system.
GSuite provides less features for identity (it bundles what is now described as the Free Edition of Cloud Identity, while the standalone/add-on product is the Premium Edition.)
You can "login with Google" on third party sites, but it involves an asking permission screen. The seamless SSO experience only works on Google's own properties.
Edit: BTW, I see this can be set up for Github Business. Does github.com not support SAML?