Migration assistant stuck?

You have not explained how you executed MA. If you used Wi-Fi that fails 100% of the time. The most reliable and fastest method is to connect the old Macs Time Machine External Hard Disk to the new Mac using a USB cable. Then launch Migration Assistant on the new Mac and follow the on-screen prompts. It works EVERY time assuming the External Hard Disk is in good shape.

How are you migrating?

Using Wi-Fi is not reliable and fails most of the time.

A direct Ethernet connection is better, but slow if you have a lot to migrate.

The best way to migrate to a new Mac, is to migrate for the old Mac's Time Machine backup.