Currently, the method used to generate a cloth config screen and integrate it with mod menu returns an <Supplier<Screen>>, and we can only use it in a depecrated mod menu api method, that is meant to be removed in 1.16 snapshots:

public Optional<Supplier<Screen>> getConfigScreen(Screen screen) {
    return Optional.of(AutoConfig.getConfigScreen(Config.class, screen));
}

Would be nice to have a method returning a ConfigScreenFactory, to be able to use this method:

public ConfigScreenFactory<?> getModConfigScreenFactory() {}

no, you can implement that lambda yourself