Hey Damián,
you can synchronise webfilter overrides (and a lot of other configuration) with FortiManager - you could essentially do a default configuration with policies, security profiles like webfilter etc, and push that out to all FortiGates, so all of them would have essentially the same configuration (with some localization for the different IP subnets the FortiGates would be in, etc)
You can do some object sharing with Security Fabric setup; the root FortiGate in the Fabric would share its objects like addresses and security profiles with all downstream FortiGates, which could in turn use those objects as well (but each FortiGate would require manual configuration of policies etc; the objects would just already exist to be used in policies).
FortiPortal (or FortiPrivateCloud) is a larger-scale solution typically used in MSSP setups; it functions as a tie-in to FortiAnalyzer and FortiManager and provides individual logins/portals to an MSSP's customers so they have access to their own configuration/devices on their premises, and the MSSP has a complete overview of all FGTs/FMG/FAZ in their possession.
It could technically achieve the same, simply because it utilizes FortiManager itself, but unless you're an MSSP managing a lot of FortiGates and looking to provide access for all your customers to the FortiGates on their site (while retaining control/visibility of what the customers are doing) FortiPortal is probably not a solution for you.
