Sight swap

[Scanker19]

Never mind.

[BPTactical]

Will factory sights from a Glock 26 fit a 19?

Glock fixed sights are basically the same from model to model. What does vary is the height. They are marked with a series of horizontal lines on the right side of the rear sight.
6.1 one long line with a short line under it.
6.5 one long line.
6.9 one long line with a short line above it.
7.3 one long line with two short lines above it.
Each sight height equates to 3" difference in POI @ 25 yards with 6.1 being the lowest POI.
Front sights are the same height IIRC.

[Scanker19]

I was more concerned about the front sight. All of the 26s i have seen have a screw on them and the 19s just pop in.

But all of the night sights i have seen fit either 9mm or .40.

[BPTactical]

Two methods of retaining front sights- Screw and wedge/tenon. The screw is self explanatory but the wedge/tenon uses a small plastic pin that expands the tenon of the sight to lock it in place.
That is probably the snap in type you are referring to.