I have seen several backpacks marketed as being for CrossFit. What on earth does this mean and in what ways could a backpack be designed or used specifically for CrossFit?
I don't personally do Crossfit, but I consulted someone who has been doing Crossfit for close to a decade and operates a Crossfit gym. She said there are some backpacks that have slots in them for adding extra weight which is primarily used for rucking. They can also be used in-lieu of a weighted vest for pull-ups or dips. Since people don't ruck all day, those slots also double as pouches for snacks and other small items. A lot of companies that built backpacks for rucking and/or hiking found a market in Crossfit so they started branding to cater to that demographic. These style of backpacks are also often labeled "tactical" or have some kind of military theme to it.
Others are special gym bags that chose to advertise to Crossfitters because people who do Crossfit are usually willing to pay a premium. Those backpacks will usually have special compartments for going to the gym like a shoe compartment, sleeves where you can slide your weight belt, and special pockets for water bottles. There's nothing specifically "Crossfit" about these other than they have a lot of compartments.
As a side note, I do own two backpacks and a duffle bag that are similar to what's described above, but instead advertised for bodybuilders. I have to say they're really, really well built. They typically have very deep pockets so you can put clothes and shoes. One of the backpacks has a thermal pouch for food. The thermal pouch also has a little slot for an ice pack. There are also a lot of compartments for whatever else. They are extremely durable. I personally use the backpacks for travel.
You have to be very careful though and look for name brands because just a quick look at Amazon and I see about a dozen knock-offs that I imagine aren't near the quality (some might be though. I've never tried). Wolfpack and King Kong are the brands that I've used. Built for Athletes is another brand that I think markets towards Crossfit that a lot of people seem to like.