PrismXR Portable Charger 30W
Sometimes, I see a really pointless, inferior product and wonder "Maybe there's a reason tons of people buy this?" The answer is almost always that those people are ignorant of the better solution. This product, the PrismXR Carina W1 Portable Charger 30W, is nothing more than a fancy-looking battery strap you can wear multiple ways that comes with cable organization tools. It's not cheap at $40 sale price ($60 regular price), and I would not have bought this... but as a reviewer, I tend to get things for free, so... yeah, I got this for free, and I decided to review it here for others to be able to find information about not just this product but a better solution.
Okay, so the product in a vacuum is not bad. It serves a purpose and is pretty affordable. It allows you to use your own head strap with no regard for battery strap options. Granted, you could alternatively buy a battery and 3d print a holder sheath for it. I personally am very spoiled on that front, because I not only have several 3d printers available to me at all times but I also have an old Vive Wireless battery with its own out-of-box clip-on sheath. Thr Vive battery, mind you, doesn't charge the Quest 3 well, and it isn't easily wearable without a belt or at least a DIY headstrap mod to wear it on your head. So yeah, I can see why someone gets this PrismXR battery. It does serve a purpose.
The real problem is the alternatives are just so much more versatile and have many QOL advantages. Battery-enabled headstraps aren't dangling a charging cable down your neck and back and require no belt to be equipped. For VR, the less barriers to entry, the better. For GoPro, having a hotswapped battery is not only cheaper than the belt but takes up less space and weighs less. Granted, you might not want to stop recording for whatever reason, but your best option for that is a bigger battery in the first place, and the Carina W1 isn't even weatherproof. For phones and handhelds, it's typically a trivial matter to attach an external battery to the backside of the device or to have a small portable charger in your pocket or purse.
Before you yell, "But it has a cooler on it!" I have to admit, that's a cool feature. Heh. 
However, it doesn't actually benefit me to have my lower back cooled when the part of my body on fire is my face. I think the cooling feature is more of a promise not to have the battery get too hot, because it sits on your lower back for VR. This isn't a selling point if the problem is due to a use case flaw and not an actual problem inherent with other batteries. I will, however, note that the cooling feature means a lot of power is wasted on keeping air flowing through the battery pack instead of powering the headset... which to me is a second flaw created by the solution to the first flaw of this belt design which is not an issue with other battery types.
If after hearing all of this, you still want the Carina W1 Portable Charger, you can buy it here. However, if you want the best experience possible for the Quest 3, I highly recommend the Binbok T3 Plus Battery Head Strap Rechargeable Battery 2x8000mAh Charging Dock for $85 ($25 coupon currently). It's not the most comfortable headstrap I've tried, but it's pretty good for a battery strap. The batteries hotswap easily and charge fast and power the Quest 3 better than anything else I tried. It isn't a popular brand, but I did an unbox video on YT for it a while ago, and after that, I've had nothing but praise for it, even after receiving many competing battery straps.