Hi all,
Thanks for your replies on my last post.
I managed to get it working after all ๐I was getting redirect_uri_mismatch.
Turns out I had too many scopes running and only https://mail.google.com/ was necessary. Allowed that in the Google Cloud Portal, filled in ID and Secret and tried again and it let me through. Sent a test mail to myself and it came through without issue. Will update if I run into anymore issues.
Sharing as a post incase someone else new runs into this problem ๐