Every step below is from an official source
Switch from Proton Pass to Apple Passwords (iCloud Keychain)
What to do at Proton Pass 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 Proton Pass, before you leave
Export from Proton Pass settingsBefore
In the browser extension, web app or Windows app, open settings with the gear icon, then click the Export tab.
How to export from Proton PassProton Support. ReviewedUse a computer, not the mobile appBefore
You can't export data from the Proton Pass mobile apps.
How to export from Proton PassProton Support. ReviewedEncrypt the export if you store or send itDuring
You can export a ZIP with a PGP-encrypted JSON file, an unencrypted ZIP, or a CSV file. Proton recommends encrypting the file if you will keep it as a backup or transfer it.
How to export from Proton PassProton Support. Reviewed
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 Proton Pass 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.