Struggling with font size of Tex Gyre

I am working on my first XeLaTeX project and I am still struggling with the font settings. I defined a new math font for a specific section unittable:

setmathfont[version=unittable,SizeFeatures={Size=9}]{TeX Gyre Pagella Math}

So my plan is, to have TeX Gyre Pagella in font size 9pt for the section defined by mathversion{unittable}. Unfortunately (and surprising to me), the size 9pt doesn’t exist for TeX Gyre Pagella and I get the following warning:

LaTeX Font: Font shape 'TU/TeXGyrePagellaMath(1)/m/n' in size <10.95> not available size <9> substituted.

Is there any way around, e.g. scaling or using a font clone, which supports 9pt? Or is there an overview, of which font sizes are available for TeX Gyre Pagella? thanks a lot!

setmathfont[version=unittable,Scale=0.822]{TeX Gyre Pagella Math}