TYPO3 Core

I would recommend to make some of the slug field options configurable via TSCONFIG

At least one Change would be required in sysext/backend/Classes/Form/Utility/FormEngineUtility.php

protected static $allowOverrideMatrix = [
        'input' => ['size', 'max', 'readOnly'],
        'text' => ['cols', 'rows', 'wrap', 'max', 'readOnly'],
        'check' => ['cols', 'readOnly'],
        'select' => ['size', 'autoSizeMax', 'maxitems', 'minitems', 'readOnly', 'treeConfig'],
        'group' => ['size', 'autoSizeMax', 'max_size', 'maxitems', 'minitems', 'readOnly'],
        'inline' => ['appearance', 'behaviour', 'foreign_label', 'foreign_selector', 'foreign_unique', 'maxitems', 'minitems', 'size', 'autoSizeMax', 'symmetric_label', 'readOnly'],
        'imageManipulation' => ['ratios', 'cropVariants'],
        //NEW
        'slug' => ['fallbackCharacter','generatorOptions','prependSlash']
    ];

This would result in an easy configuration of slug options via TSCONFIG f.e.

TCEFORM.pages.slug.config.fallbackCharacter=_
TCEFORM.pages.slug.config.generatorOptions.prefixParentPageSlug=0

Christoph