Unique settings for same field type across models

Is your feature request related to a problem? Please describe.

I have different kind of pages (=models). Each page models have a unique URL / slug.

Describe the solution you’d like

I’d like to set a unique constraint on a field across different models.

Describe alternatives you’ve considered

I could merge my different models into a unique one and ask the editor to ignore some fields but this leads to bad UX.
I can check the uniqueness during the build but I do not have any way to give feedback to the editor about why the build failed.