Every step below is from an official source
Switch from LastPass to Google Password Manager
What to do at LastPass before you leave, what Google Password Manager 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 LastPass, before you leave
Export your vault from the LastPass websiteBefore
Log in on the LastPass website, open the Account tab, then go to Fix a problem yourself > Export vault items. In the previous layout, go to Advanced Options > Export.
How do I export my vault data while logged in via the LastPass website?LastPass. ReviewedConfirm the export from the verification emailDuring
LastPass emails you a Verify export message. Click Continue export in that email within 10 minutes, then go back to your vault and run the export again.
How do I export my vault data while logged in via the LastPass website?LastPass. ReviewedAllow pop-ups so the CSV file downloadsDuring
After the export, your sites and secure notes show in a browser page. If LastPass pop-ups are not blocked, a CSV file with your vault data also downloads.
How do I export my vault data while logged in via the LastPass website?LastPass. ReviewedNote that TOTP codes are not exportedBefore
LastPass does not support exporting the one-time passcodes (TOTP) you generate inside your vault.
How do I export my vault data while logged in via the LastPass website?LastPass. Reviewed
At Google Password Manager, when you join
Import a CSV file at passwords.google.comDuring
Go to passwords.google.com, select Settings, then Import, then Select File. Choose your file and select Import. Only .CSV files can be imported.
Import passwords to your Google Account - Google Account HelpGoogle. ReviewedImport up to 3,000 passwords at a timeBefore
You can import 3,000 passwords at a time. Your Google Account can store up to 10,000 passwords.
Import passwords to your Google Account - Google Account HelpGoogle. ReviewedDelete the CSV file after importingAfter
After the import, delete the .CSV password file. Otherwise anyone with access to the device can open it.
Import passwords to your Google Account - Google Account HelpGoogle. ReviewedSearch by site name for missing passwordsAfter
Not all app and site names move into the right field. If you can't find an imported password, search for the app or site name.
Then: everything else the switch affects
The steps above are what LastPass and Google Password Manager 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.