How to have one login page for multiple tenant regions?

Use Case:
We have customers who want to store their data in US or Australia regions. We want them to be able to login from the same login page. Also, some customers use SAML/Social/Enterprise connection and we don’t want to show their login buttons on the login page.
We’re not sure that they will always have some fixed domain for their users. So we don’t want to depend on Home Realm Discovery.

Our Current Implementation:

  1. We have two tenants, Tenant 1 (US region) and Tenant 2 (Australia region).
  2. Our web app does not contain any sub-domains for US and Australia regions. For example, the URL is https://{domain}.com
  3. There is our own login page in our web app where user enters their email. It calls our own API which returns the Auth0 tenant and connection information for this user.
  4. User is then redirected to Auth0’s Universal login page with pre-added “connection” and “login_hint” params, to open user’s connection automatically (database or SAML/Social/Enterprise connections). This overcomes the limitation of Auth0 that we can’t do Home Realm discovery like automatic connection detection without specifying a domain.

Question

  1. Is this the correct way to do this?
  2. Can Auth0 provide a single login page for multiple regions. You can take a look at Zoho login page (Zoho Accounts).