You can get a pretty good sense of what the learning curve of a tech stack is by spending a few days or a week with it solving a small real world app problem. For example, building a login screen of an app will give a sense of laying out a screen, navigation, calling a data endpoint, and how easy it is to find information in the api and docs to solve a problem.
Considering how long it takes to build an app, spending that initial 20-40 hours in solving an app problem is the best sense you going to get because other people will come to either of these frameworks with different mindsets, backgrounds, and more importantly the ability to learn faster based on experience.
As an example, I wouldn’t even advise anyone coming to mobile learning a cross platform framework first without learning native. But again, my background with using cross platform frameworks is what influences that opinion. (I’m currently have been doing mobile dev for the last 5 years after doing web dev for 13 years)