If you want a more stable platform with your pistol, the first thing that gets to your mind is get a carbine conversion kit such as the RONI or the HERA 1911. They do turn your Glock or 1911 into a mini carbine that you can attach weapons accessories with. But then it is not a pistol that you can holster anymore after using it.

Flux Defense has the answer to that. At the SHOT Show 2019, the Flux Brace attracted the attention of trade visitors for its simple, patent-pending design. Available for the Glock G17, 22 , 31 , 34,  35, and the G19 version in the works, it is an auto-deploy brace with its spring mechanism and is mainly made of Chromoly steel with Cerakote finish.

While it is considered to be holsterable, it works best with the reversible Flux Brace Holster for it as it guards auto-deploy button to prevent accidental ejection.

The Flux Brace is easy to ad to the Glock pistol with its single pin quick installation though the company advises that you watch the instruction video before installing it to insure you do it the right way.

Once installed, it can be deployed quickly with a push of the button and the shooter will notice a “Keep Face Back” at the end of the brace to allow for the pistol’s slide to cycle. It also deploys with a force so it is best to keep your face back. It also reminds you that it is a stabilizing brace not a stock with the written “Not A Stock” on the rear.

Flux Defense says that it is compatible with most light, but recommends that users not to it use on TLR-H1 and similar Streamlight models.

Honest Outlaw got a review of this if you're looking for a review:

It’s an expensive brace as it costs US$259.00 with the optional Flux Brace Holster priced at US$89.00. It cannot be used with the Gen 1 to 3 Pistols. No idea if it can be installed on the airsoft Glock pistols without some modification.