I previously did a series on using ZeroTier to create a highly scalable site-to-site VPN solution using ZeroTier on VyOS. This included creating multitenancy and segmentation using MPLS. You can find those articles at these links:
Dynamic Multipoint VPN with ZeroTier and VyOS
Dynamic Multipoint VPN with ZeroTier and VyOS – Part 1.5: Persistent ZeroTier Installation
Dynamic Multipoint VPN with ZeroTier and VyOS – Part 2: MPLS
Dynamic Multipoint VPN with ZeroTier and VyOS – Part 2.5: Microsegmentation
Dynamic Multipoint VPN with ZeroTier and VyOS – Part 3: Regional Design
Dynamic Multipoint VPN with ZeroTier and VyOS – Part 4: More ZeroTier
This Article focuses on using ZeroTier as more of a closed solution for a multisite VPN solution (no additional routing protocols; all routing handled by ZeroTier ).