It is working!
Just add ble and cordio to requires in mbed_app.json. In my case (nRF52832) it was:
"requires": ["bare-metal", "events", "ble", "cordio", "cordio-ll", "cordio-nordic-ll" ],
You can also enable other APIs like described here: https://os.mbed.com/docs/mbed-os/v6.0/bare-metal/using-the-bare-metal-profile.html#2-adding-apis
All available APIs for bare-metal are listed here: https://os.mbed.com/docs/mbed-os/v6.0/bare-metal/index.html
In my case i only was able to compile with GCC at the moment. Other platforms should already work with ARMC6. Here is an overview: Some Mbed OS 6 targets don't compile with Baremetal profile · Issue #13099 · ARMmbed/mbed-os · GitHub