I do not what exactly you mean by generating schemas over the UI. As you say I expecting it was possible to achieve this via a client app (or CLI which I do not use yet). A few days later I think this was more proposal to simplify use case when you want to add some common functionality to your application and you can do it basically instantly without even touching code. Something like, you want to add Identity to your project and you want to have it as part of your application (for some project I think you do not need separate project/application etc…). And then it can be something like
Squidex.Extensions.Identity and with one line
services.AddSquidexIdentity(..config..) you have an identity in your project.
Another example can be adding a blog scheme to an already existing application. For example, someone starts with whatever project and later decides to provide basic blog functionality, and this way they can start with just a few seconds, and even without developer they can start filling content. Same for simple eshop solution.
Obviously, I do not if this how common this use case can be and for best user experience it will be much better if someone (community?) prepare for example entities and datastores as NuGet package then it will be really great (do not expect this from you of course).
I do not look to another headless CMS (I discover headless CMS just with Squidex and I really like it so far) so I do no know if something like this can is available somewhere and if it could be considered as an advantage again competition.