So it's essentially a more seamless and granular analog of a VPN? A device sits in front of the network and requires some sort of authenticated handshake (ideally all SSO) before passing packets through to a target endpoint?
The other salient point is that all connections are established outbound through a broker, and importantly this is the case from both sides: The appliance at the terminating end of the tunnel establishes reverse tunnels to the broker for the connections, so it's never "exposed to the internet".
The broker can then push to your SIEM or whatever so you can have your SOC log jockeys harass your employees for accidentally leaving NordVPN on after watching international sports.
There are actual benefits: You can do things like allow logins to system A from anywhere, but system B only from your home country, you can do JIT network access requests, etc... but mostly it's vendor marketing to get you to spend too much money.
My way of mapping it to VPN mindset is "per app clientless VPNs straight to where the things are hosted". In an extremely open ruleset with all of the servers on a corporate network this could theoretically devolve into "a traditional clientless VPN to the office".
They can be implemented using a variety of technical patterns but they all share a common "each request is authenticated, encrypted" property instead of "anything goes once the tunnel is up" property.
And yet every customer of mine have some of their servers on a VPN. At the very least they enable ssh only on ports on the private network.