What metrics do you track to measure the success of a product launch, and how do you set-up processes to respond to the early market feedback?

The types of metrics you would measure are quite subjective to the Go-To-Market strategy for your business.

For example if your business goal is to drive distribution and new signups your would consider things like new activations, org retention, as well as weekly account usage and key moments

On the other hand if your launch is tied to driving things like product led monetization or upsells, than you want to look at things like upsells, ACVs and time to complete trials

Finally if you are primarily selling into enterprise accounts via new product add-ons, this would entail a diffrent set of KPIs including attach-rates, contract value and time to implementation

tl;dr Metrics are really dependent on you Go-To-Market Strategy thats associated with your launch