Hi @Yoursnani ,
You could use the group id in the Items property of the people picker to filter the group members that can be added, and set the Update property of the person_DataCard to add the selected value to the SharePoint list.
I have test for your reference, please try the following workaround:

Items property:
Office365Groups.ListGroupMembers("Group ID").value

Update property:
{'@odata.type':
"#Microsoft.Azure.Connectors.SharePoint.SPListExpandedUser",
Claims: "i:0#.f|membership|" & DataCardValue2.Selected.mail,
Department: "",
DisplayName: DataCardValue2.Selected.displayName,
Email: DataCardValue2.Selected.mail,
JobTitle: "",
Picture: ""
}
Best Regards,
Jessica Gu