Yes, you must have a HUB to do the BGP route for all the sites/branches.
In my case, I have it in MS Azure - Fortigate VF so there will not be any dependency if the branch or sites is down.
MS Azure - Fortigate VF provided 99.99% uptime 🙂
All my branches are using Meraki MX - I mean full Meraki.
Only the cloud I'm not using vMX because vMX is just a VPN concentrate without any security much there.
But there's 1 thing that is beneficial to use vMX from Meraki, VPN will auto comes up with the secondary internet when your primary internet is down in any of the branch or sites. Fortigate VF doesn't, you need to manual setup.
We choose Fortigate VF because we forward the traffic towards the Fortigate because it performs all the security check such as, virus, malware, hackers & so on.