I am aware of PowerShell Script to unhide user from GAL by doing so (example):
Set-AzureADUser -GivenName $first -Surname $last -JobTitle $title -Department $dept -ShowInAddressList $true
However, we are interested in doing this using the REST API. Is that possible? Not sure if it matters but in our case, this is for a set of Azure AD B2B users.