Experiences with profile cards in Dynamics 365 v.9.1

Today I was testing out the profile cards feature and analysed how Microsoft implemented it as there is only little information to find on docs.microsoft.com, like this article:
https://docs.microsoft.com/en-us/dynamics365/customerengagement/on-premises/admin/enable-profile-card

While using the profile cards I experienced a behavior that was not really self-explanatory for me and my colleagues. Thanks to Chrome DevTools I was able to have look behind the scences to find more information on how it works.

Key findings

If you use a contact lookup field on an entity form and...

• select a contact that has the field "emailaddress1" filled you will get a persona card popup
• if the contact has "emailaddress1" not filled the persona card popup will not show up

For system users there are two fields that are used to show the persona card popup:

• internalemailaddress
• azureactivedirectoryobjectid

The following snippet helped me identify those fields and dependencies:

t.prototype._getQueryOptions = function (e) {
 switch (e) {
 case "contact":
  return "?$select=emailaddress1";
 case "systemuser":
  return "?$select=internalemailaddress,azureactivedirectoryobjectid"
 }
 return ""
},
t.prototype._getLpcIdentifiers = function (e, t) {
 switch (t) {
 case "contact":
  return {
   smtp: e.emailaddress1
  };
 case "systemuser":
  return {
   smtp: e.internalemailaddress,
   aadObjectId: e.azureactivedirectoryobjectid
  }
 }

Further I found that this file:
/uclient/scripts/livepersonacard.js?v=1.3.2399-191022-211210
provides information that it leverages Microsoft Delves Live PersonaCard App or feature to display the popup, which looks similar to what we can find here:
https://developer.microsoft.com/en-us/fabric-js/components/personacard/personacard

As Office Fabric JS offers a nice framework for controls the idea is not far away to use the components provided there for your own PCF controls which there are already a few controls shared on https://pcf.gallery like this DatePicker control: https://pcf.gallery/date-picker/