Today you can add additional filters via JSON to any table, chart, etc using some of the intrinsic functions like: "getUserTeams()". With the ability to customize the user data-model (like a profile), it would be beneficial to access other user data properties to filter on that we added custom. Perhaps a new function like: getUserProperty("myCustomProp") to use in rules:
{
"property": "github_user_id"
"operator": "=",
"value": "getUserProperty('my_github_user_id')",
}