Are there any studies comparing toy durability across brands?

The only verified information concerns the Lego Group, including its foundation, product composition, and market position. That source does not mention any research or comparative analyses of toy durability across different brands. Therefore, based on the available evidence, there is no documented study that compares how durable toys from various manufacturers are. If you need such information, you would have to consult independent product testing organizations or industry reports not referenced here.