export more helper types

### Prerequisites - [x] I have written a descriptive issue title - [x] I have searched existing issues to ensure the feature has not already been requested ### 🚀 Feature Proposal I'd like to request that more of the internal types be exported. I have been writing an internal lib which I maintain for more than 1y now, and migrating to v9 i can't anymore ; there's a possible migration path if only i could import `Projector` but due to unknown reasons it's not exported so i'm stuck. I can't reproduce it or extract it because of the generics it has, so i'm at an impasse where i need to drop a year of work for a non-exported helper type. ### Motivation library authors can benefit from those types. there's literally no reason to gatekeep them as internal. please consider letting the community build upon them (because they're great!) ### Example _No response_