There's been a number of short 12 gauge shells brought out over the last century.
The Brits were first. Back around the 1920s, I believe, the fad was a super light 12 gauge with 2" shells holding down to 5/8 oz of shot, tho most used 1 1/16 oz,like longer sporting shells. Here we use 20s and 28s for the same effect. Of course, lots of light Brit and European doubles were built for their standard 2 1/2" shell also.
Back around 1980,the Feds tested 2" shells in some short shotguns they had, mostly 870s, IIRC. Results were mixed. One agent I knew liked the short shells in his standard 870, and was a master at getting center hits in very short time frames with it. BTW,the official FBI buck during this time was #4, not 00.
After the Feds turned down the concept of using short ammo, those shells were marketed as "Bantam Mags" or something else testosterone inducing. Feeding reliability was suspect, tho patterns seemed excellent compared to "Generic" 00.
As to the new stuff,I'm a hidebound conservative. The possibility of feeding probs weighs more heavily than the supposed benefit of having one more round in the mag,IMO.