I’m also a CLI old timer, but there’s undeniable utility in having a Postman-like collection to test drive a mobile app API. You can save state from responses and use it in subsequent requests. E.g. log in, save the access token, create a post, save the id, post a comment under the post using the id. It’s all very useful, to say nothing of the fact that you can give said collection to non-technical stakeholders and they can solve a lot of their own problems without going to get one of the engineers to Do A Command Line(tm).

All that said, I wouldn’t touch Postman. Last time I needed something to fit this bill I looked around to find the open source equivalent and found Bruno.