They do, they expose it via an API, so you can use IFTTT (or anything you make that's similar to this) to optimise when you use power.

This website does some analysis on the pricing: https://www.energy-stats.uk/octopus-agile/

The useful part is that, if a user of the tariff is sufficiently engaged, not only do they save money, but by shifting their demand to follow supply it helps with the increasing adoption of renewable sources.