The important metrics is peak requests per second. 14M / day sounds impressive, but it’s only a sustained 160 per second which literally any language and framework can handle on the lowest end hardware.
Even pre ai you could toss together a decent cache in about a minute using ets or similar, and faster with a solution like cachex (which was basically what you'd build yourself but packaged into a neat little bundle)
It is open-source:
https://github.com/etalab/transport-site/tree/master/apps/tr...