We had a requirement in a project to authenticate users in a site collection based on Country claim presented by a User.
Below powershell sample is to add a US country claim value to a Visitors group of a site collection to allow any users from US to get authorized to view the site.
$web = Get-SPWeb "https://SpSiteCollectionUrl"
$group = $web.Groups[“GDE Home Visitors“]
$group.AddUser($claim.ToEncodedString(), “”, “US", “”)
Note : for this solution to work you we have used an ADFS solution which pull our calim values from Enterpise directory and sends SAML claim to SharePoint.