According to JEP 401 spec,
a value class can be abstract and non-sealed

8.1.1 Class Modifiers
A class declaration may include class modifiers.
ClassModifier:
(one of)
Annotation public protected private
abstract static final sealed non-sealed strictfp
value

However, the compiler rejects the following code:

abstract sealed value class Q permits A{}

abstract non-sealed value class A extends Q {}

value class B extends A {}

public void main() {
    new B();
}

java: illegal combination of modifiers: value and non-sealed