It's not really something netflix even came up with. I know I saw Akamai boxes in ISP datacenters way before netflix got into streaming
That is true. I didn't think that they were doing it was the trade secret but the way they were doing it might be, unless that is pretty standardized too. I don't really know.
The fact that they have and deploy boxes isn't the secret. It's the hardware configuration and software integration which is the sauce.
Most CDN operators do this, including apple which also has a public website about it - https://cache.edge.apple