is there any way to use variable fonts in houdini?

Yes, just paste a complete file path to the font into the text field. If you hover over the Font label, you'll see a tooltip that reports the parameter's name as file.

Ah.. thanks for you reply.. but i think
not exectly what i meant...

i `m wondering if there is a way to use a "variable font's" adjustment possibilities... usually it`s e.g. seamless
font-weight-adjustment...

supernice feature of some modern fonts like e.g.
https://fonts.google.com/specimen/Albert+Sans/tester [fonts.google.com]

and admittedly there are not too many applications supporting this. but i`d be more than happy to use it in houdini also..

Depends on what you mean by "use". Qt only added support for variable axes and font features in Qt 6.7 and 6.6 respectively. The next version of Houdini will upgrade to Qt 6.8, so you'll be able to use them in custom Qt UIs in the next version of Houdini.