Signing in with Google is only needed to attach images or files in chat. Before continuing, please note:

• Your chat messages and any attachments get stored so you can review or delete them later.
• Attachments under ~301KB are stored fully; larger ones only keep the file name — not the content.
• Stored chat data is automatically deleted roughly every 5–7 days, and permanently — no backups are kept.
• You can delete everything yourself anytime from More → Account.