NIST SP.800-207: "Zero trust (ZT) is the term for an evolving set of cybersecurity paradigms that move defenses from static, network-based perimeters to focus o

NIST SP.800-207: "Zero trust (ZT) is the term for an evolving set of cybersecurity paradigms that move defenses from static, network-based perimeters to focus on users, assets, and resources... [it] assumes there is no implicit trust granted to assets or user accounts based solely on their physical or network location [and it] focuses on protecting resources (assets, services, workflows, network accounts, etc.), not network segments, as the network location is no longer seen as the prime component to the security posture of the resource." So while I think you 1st sentence is a bit whooly, your 2nd is bang on. Wireguard (and ergo Tailscale) is focused on connecting devices, not services, and being on the mesh gives you access to other devices/endpoints. To achieve zero trust networking you also need micro-segmentation, least-privilege, attribute-based-access control, authenticate/authorise-before-connectivity as part of the overlay.