What would be a good way to do that? I wonder.

In the same vein, in Angular, consuming webservices that have a "proper" REST API (if there is such a thing, but still, this is nice) is easy with Restangular (https://github.com/mgonto/restangular). Not having such a thing has costed me much time during hackathons, during which competition using it was wrapping webservices at the speed of light while I was plodding along.

Is there such a thing in Pharo?

Seaside REST

No: this is for exposing endpoints, not consuming them. See Restangular.