I think they look interesting, but for the asking price, just too steep to add for a range toy.
I say range toy because I don't really see a practical use for a sub-carbine conversion "husk" into which your pistol is mounted. All the great reasons for having a pistol are eliminated - primarily concealment. With a modicum of practice most people can shoot a handgun quite accurately well beyond 50 yards, so you don't really need a stubby stock device for that.
For the money, if you live in a free State, an AR "pistol" with arm brace comes in as small and light, but with a whole lot more punch and seamless firepower. You can snap in a 60 round Magpul drum or 40 round stick. There's even a nifty folding adapter that allows you to fold the buffer tube for compact storage, then lock it open before firing. Using a Sig brace as a shoulder support is legal. Even a stubby 7.5" barrel in 5.56x45 is clocking around 2,300 fps with garden variety surplus ball, but where a pistol AR really shines is when you drop back to 40 grain slugs that can be sent zinging down-range at closer to 3,000 fps - from that same barrel length! By now pretty much anyone can "bolt together" an AR of whatever size and pattern using either an 80% lower or store-bought. For those living where it's legal it's the way to go if you want a compact sub-carbine you can carry in a gym bag.
For less than the cost of one of the kits you can SBR an AR or AK and have the super-short barrel with stock! You end up with REAL firepower using "pointy" bullets carrying gobs more energy!
If you don't think the 5.56x45 is potent enough, well, there is the 7.62x39, and the 300 Blackout with 8" barrel - my particular favorite! Anyone tells you such configurations have no purpose or can't be used effectively is only revealing their lack of experience.
Even in "pistol" calibers, an AR beats a RONI conversion...9mm, 40S&W, 45 auto, 10mm....and prices right now are the lowest I've ever seen. Just a few years ago there were few Glock magazine options and of the ones available, the cost was outrageous compared to standard Colt mag systems. Now, you can find lowers for Glock mags on clearance! However, a blow-back 9mm carbine (pistol) is going to be heavier than a 300 AAC carbine (pistol).
So for the money you're going to spend, I just don't see any practical value other than just to have one. Being a "shell" means you still an actual gun to make the thing work, and the price of the shell puts you most of the way toward almost any DIY AR pistol you might want.
