What you want is exactly what dither brushes are meant for, and using a specific gradient position is the workaround, the dither gradient feature is literally not designed for this, it’s meant for keeping gradients to a set palette, not for painting a specific dither.
However, it’s a damn convenient workaround (especially since adding matrices is a bigger pain than it ought to be), and since you can set min/max for angle and size, I don’t see why the same shouldn’t be possible for dithers. It would even be convenient when using a tablet for setting a subrange of the gradient to use (useful mostly with dithers rather than regular gradients).
Also, for inputs without pressure, there’s the velocity option, which lets you fake pressure with the speed of your cursor. It’s not bad, but it’s very inconvenient for what you need, since you’re looking to use a specific value, and velocity is harder to control precisely than pressure.