Track Sign-in in blend application

Hey Support Team.
I want to track Sign-in in my blend application in google analytics. I didn't find any Sign-in event in blend developers documentation.

How can I track sign-in in the blend application and send stats to google analytics? Can we add custom code such as Google Tag Manager code on the sign-in page or is there any alternative to track sign in?

Looking forward to your response.
Cheers,

Anas
Marketlytics