Wiping an SSD

In preparing a MacBook Pro 2017 15-in for sale, I am following the instructions at the following link to wipe the SSD:

“FileVault Keeps Your Data Safe”
https://www.backblaze.com/blog/how-to-wipe-a-mac-hard-drive/

Am I correct in assuming that when the FileVault key is deleted (after unlocking the drive in Disk Utility), the data is useless even to someone who has the login password?

Also, are previously deleted files likewise useless?

Thank you,

David

In a word, yes. Everything on the drive is encrypted so would take a Herculean effort to recover and decrypt.