i tend to prefer the following when working with non-traditional class constructors:

data class Foo {
    companion object {
        operator fun invoke(): Foo {
        
        }
    }
}

mmm kinda looks hacky to me

yeah, a large portion of it comes down to how unconventional kotlin's companion objects are

I’d probably suggest doing

fun Foo() = Foo(someValue)

instead

For me it looks fine, pretty popular idiom

fun Foo() = Foo(someValue)

is also fine, but it will conflict with class if class has the same signature of constructor, so you cannot have private constructor and builder with some additional logic:

class Foo private constructor(val value: String)

fun Foo(rawWalue: String?) = Foo(requireNotNull(rawWalue))

Isn't

Foo()

via companion object

invoke()

still just as ambiguous if the class has that same constructor?

No