Yes, the brand would love you to show your followers the product! Preferably removed from the packaging and in use.
Get creative with your content and post something that fits organically into your feed so you keep the post public.
We don't just want you to try a product, post a random picture of it, and then take it down after 2 weeks because "it doesn't fit in with my feed". Reviewing products can be great content for your feed, keep followers interested, and attract brands. Post wisely, show off awesome stuff you've been gifted, and love what you do :)
Check out this awesome example of how creator @2lilbrobros authentically incorporates collab products into their feed: