I develop plugins for a specific nocode proprietary platform, sixth year now doing it for a living, 95% of all apps use plugins, which are the custom code interface, the escape hatch.
The ones that don't are very CRUDy apps with no remarkable features, like just some pretty design to input and show information.
And most apps use about 10 to 20 plugins.
I'd be really interested in knowing how often escape hatches like that are actually used. I'd guess it's less than a fraction of a percent, if ever.