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In case anyone is interested, this can be done on PS8.1 editing "/classes/formCustomerAddressFormatter.php" file.
Around line 90 add:
$formField->setType('tel');

        foreach ($fields as $field) {
            $formField = new FormField();
            $formField->setName($field);

            $fieldParts = explode(':', $field, 2);

            if (count($fieldParts) === 1) {
                if ($field === 'postcode') {
		    $formField->setType('tel');
                    if ($this->country->need_zip_code) {
                        $formField->setRequired(true);
                    }
                } elseif ($field === 'phone') {
                    $formField->setType('tel');
                } elseif ($field === 'dni' && null !== $this->country) {
                    if ($this->country->need_identification_number) {
                        $formField->setRequired(true);
                    }
                }