Hi davess,
The primrose would likely have an inherent fire barrier that doesn’t use any added chemicals but they would be the most reliable source of more specific information because there are many variations of inherent fire barriers that are used in the industry. There is also more about fire barriers in post #2 here and the two posts it links to at the end.
The choice between wool and non wool would be more of a preference and budget choice than a “better/worse” choice since both would be fine but I personally like the benefits of wool because not only can it act as a fire barrier but it also is one of the best temperature and humidity regulating materials that can help to maintain a healthier microclimate which can contribute to deeper and more restorative sleep.
Phoenix