Just been back in Ch yesterday from Thailand. Piyavate hospital was my good choice. Came at 8 am and had the result by 5 pm the same day. Friendly and professional staff. 2500 thb for RT PCR in English and add 500 thb if you want a fit to fly (which you don't need to enter Switzerland).
They ask to see your test at check in .....but nothing has been asked to me when I passed immigration at zh airport ....