I think for row manipulations they end up looking either like Vinyl records or you create a DSL for row expressions - sort of like Polars. I’m not partial to either approach but it seems the DSL would make for a simpler UI depending on the target audience.
One of the ideas I’ve been toying with is, in the long term, doing program synthesis to generate data transformations sort of like Cloud Data prep/Trifacta. A typed row manipulation API does make that synthesis problem a little easier (I think). That’s pie in the sky though.