I invite you to look into feature flagging.

It is entirely viable to never have more than 1 or 2 open pull requests on any particular code repository, and to use continuous delivery practices to keep deploying small changes to production 1 at a time.

That's exactly how I've worked for the past decade or so.

> It's very normal to be working on a feature that depends on a not-yet-merged feature.

Oh sure, many bad ideas and poor practises such as that one are quite "normal". It's not a recommendation.