/bonus 50

There are very less resources about how to build an app for cal.com. Do you have any resources that can dive deep into it.

I reckon it would be similar to how cal.com integrates with Microsoft Teams (work accounts). Microsoft has an API to enable creation of a Skype meeting or Microsoft Teams (personal accounts) meeting link for users authenticated to their account. I would suggest the same way you add a calendar to your Microsoft 365 account, you can do the same for your Outlook.com or Hotmail account and connect to this API.

Details:
https://learn.microsoft.com/en-us/graph/choose-online-meeting-api