I plan to visit a friend in Austria. Is there any way for me to grant my friend a medical power of attorney in case I become incapacitated while there?
In Colorado, you can create a Health Care Directive, or Medical Power of Attorney naming your friend. That would be recognized and enforceable in Colorado. However, whether that would work in Austria is a different question.
You should investigate what Austria permits for Medical Powers of Attorney and consider doing both, a Colorado one and one that is recognized in Austria.