Preventing Data Recovery from a Factory Reset Mac

[Appledoesnotlisten]

I am going to sell two Macbooks that are now hosting a bunch of sensitive info.
i am aware that certain apps can recover deleted data, even after a factory reset, and want to prevent that from happening to my computers.

What are the most reliable and yet not overly time-consuming ways of wiping everything out securely?
Maybe do a Factory Reset, sign up with a burner Apple ID and download 500Gb of random files so that they overwrite previosly existing data?

Thank you!

 

[chscag]

Take a look here:

Best File Shredder Software For Mac In 2021

Do you want your deleted data to stay unrecoverable forever, if yes, then you must have a file shredder app for you. Check out the list of file shredder software for Mac.

blogs.systweak.com

 

[monokakata]

The way I understand it, if you use File Vault to encrypt the MacBooks, and then do a clean install of a new MacOS, you're protected against anything short of NSA nerds.