Email template for sending welcome email when a user is confirmed

I want to send a nice welcome/onboarding email only when the user is confirmed, not when they are signed up. It would be very helpful if we can have an email template that gets sent out when the user is confirmed.

Currently, as a workaround, I am assigning a special flag to user_metadata when a user is signed in for the first time. Then there's a webhook listening to the UPDATE event on the auth.users table. When the value of the special flag is set to true from false, I am sending out a welcome email. This works but is extremely inefficient because this event will be triggered every time a user logs in, since last_sign_in_at field gets updated.

I also looked into listening to a change in confirmed_at field in the users table, but I never get an UPDATE event when confirmed_at is updated if a user logs in with Google OAuth.