Is there an modified teensy firmware for the arduino

Yeah so my question is.. Is there an modified teensy firmware for the arduino ?

Or is there any other way to run teensy-code on a arduino (UNO). Any ideas and suggestions are very welcome :)

I don’t understand what you’re asking…
The Uno has significantly different hardware than a teensy (I’ll assume you’re talking about the mega32u4-based teensy), so it’s not capable of supporting (for example) some of the usb hacks that teensy can do. (now, a leonardo…) The teensy-modified arduino environment (“teensyduino”?) and the normal Arduino environment should support similar sketches without many changes.