Can be installed on the glock pistol

Hey Kevin ... I don't think you want to put this red dot sight on your glock because it would be just too big and too heavy for a pistol. I would not recommend it. Hope this would help you out.

Is it a nerf gun sight?

Hello, I am a nerf gun modder (somewhat) and yes, you can use this on a nerf gun, however, you need a picatinny rail to use the sight. This is a link to the Worker Picatinny Rail for the Retaliator. https://www.amazon.com/Worker-Picatinny-Weaver-N-Strike-Retaliator/dp/B019B63KJ6/ref=sr_1_6?s=toys-and-games&ie=UTF8&qid=1522598908&sr=1-6&keywords=worker+picatinny+rail+nerf

Will this work on a springfield xds 45?

No, assuming you actually got it mounted which would be it’s own headache, it will not hold zero against that kind of force and WILL burst into pieces within the first 100 rounds

How does this sight power on?

There is a "G" and "R" on the dial in the center - that is the off position if they are lined up on the marking on the left hand side of the sight. As soon as you turn it in either direction you will get progressively brighter images in either green or red depending on the direction (CCW or CW) that you rotated the dial. There is no instruction detailing this but you will figured it out by turning the dial.