As far as I knew there were only three handguns chambered in 5.7x28mm: Masterpiece Arms Defender, Excel Arms Accelerator and of course the first one – FN Five-seveN. But it turns out that there is also a Ukrainian pistol called Fort-28 chambered in this caliber.
The Ukrainian company started designing this gun back in 2015. It is a double action only polymer-framed semi-auto pistol. It is either striker-fired or has a shrouded hammer just like the FN Five-seveN. The pistol feeds from a 20 round magazine. What we can see from very few images of this pistol is that it has a Glock-style trigger safety and a Picatinny rail section. You can also see the slide release lever and what looks to be a disassembly lever. The latter is pretty reminiscent of the safety selector of FN’s pistol. However, I think it is a disassembly lever because there are no safety position markings and there is no other visible means to disassemble the gun. Fort-28 also has a loaded chamber indicator. The pistol’s overall length is 7.9″ with 4.5″ barrel length.
On the manufacturer’s website, the action of this pistol is described as “semi-free bolt”. It is a direct translation from Russian, that’s why it doesn’t make much sense. So the gun has a delayed blowback action. It is not specified whether it is a roller delayed or lever delayed or anything else.
Overall, the gun seems to be heavily inspired by the FN Five-seveN. Unfortunately, there are no images of the internal parts and no detailed description of the gun by the manufacturer.