To import devices enrolled in the configured Apple DEP account to the Hexnode portal you have to initiate a DEP sync.
Go to Enroll > All Enrollments > No-Touch > Apple Business/School Manager > DEP Devices > Sync with DEP.
The automatic DEP sync happens daily at 12:10 am UTC.
Yes, you can configure different DEP accounts in Hexnode. Thus, even if your Apple devices are registered under different DEP accounts, all those can be enrolled in Hexnode.
For configuring the multiple DEP accounts, please navigate to Enroll-> All Enrollments-> No Touch-> Apple Business/School Manager-> DEP Accounts and click on Configure DEP Account. Now please follow the procedure for completing the configuration.