Don’t worry — there are specialized Mac data recovery tools that can help you recover data from an unbootable Mac, such as 4DDiG Mac, iBoysoft, and Disk Drill. To perform data recovery, you’ll need a working Mac and a USB drive or external hard disk. Be sure to do your research before choosing a recovery tool, as success rates can vary. I’ll walk you through the steps using 4DDiG Mac as an example.
Step 1: On a functional Mac, download and install the tool. Then, click "Crashed Mac" from the left panel.
Step 2: Insert the USB drive into the bootable Mac's "Bootable drive" option, and select the one you just installed by clicking Start. A notification will appear reminding you to back up your data. The formatting process will begin, and a bootable drive will be created.
Step 3: Insert this bootable drive in the Mac that stuck on loading screen and boot it by holding the "Option" key. Release the key and select "4DDiG for Mac Data Recovery" to boot the disk circle when entering the plate choice interface. Presently you can get the data by tapping on "Export."