How do you figure? An unknown actor presumably had full access to your email inbox for a non-zero amount of time and the proper remediation is "nothing"? If I was concerned this had affected me I would right now be changing my passwords to ____everything____.
Although I guess if you had a circular recovery chain of this google account depending on a different email that depended on this google account, the attacker could use your email to recover the other email then use the other email to recover this google account. So it might be wise to change the passwords to everything.
If your email account is compromised, any service that do password resets via email confirmation, are potentially compromised by whoever has access to your email via OAuth.