Every step below is from an official source
Switch from Google Password Manager to Apple Passwords (iCloud Keychain)
What to do at Google Password Manager before you leave, what Apple Passwords (iCloud Keychain) needs when you join, and everything else the switch touches. Your full plan is built in your browser and stays there.
Official sources reviewed . How we review sources
At Google Password Manager, before you leave
Export passwords from Chrome on a computerBefore
In Chrome, go to More > Passwords and autofill > Google Password Manager > Settings. Scroll to Export passwords and select Download file.
Delete the exported password fileAfter
If you don't delete the password file, anyone who uses the device can open it and see your passwords.
At Apple Passwords (iCloud Keychain), when you join
Import a CSV file into Passwords on MacDuring
Export your passwords from your old app as a CSV file. In the Passwords app, choose File > Import Passwords from File, choose the file, then click Import.
Import passwords from another app into Passwords on MacApple. ReviewedReview passwords that didn't importAfter
Imported passwords won't replace ones already in the Passwords app. You can review any passwords that couldn't be imported.
Import passwords from another app into Passwords on MacApple. ReviewedDelete the CSV file after importingAfter
When the import finishes, Apple's steps have you delete the CSV file to protect your accounts.
Import passwords from another app into Passwords on MacApple. Reviewed
Then: everything else the switch affects
The steps above are what Google Password Manager and Apple Passwords (iCloud Keychain) say. Your full checklist adds the accounts, codes, payments and devices that depend on your password manager, in a safe order. It's built from your answers, in your browser.