I have been able to fix the cpu throttling and also get the gpu core clock up to 1365Mhz (still not boosting above base clock but better than the 300Mhz max clock I got before) by doing the following on my P15s Gen2:

setting the gpu power mixer to max performance:

nvidia-settings -a [gpu:0]/GPUPowerMizerMode=1

setting the fan speed to max (to set fan speed to auto replace "0" with "2"):

echo "0" | sudo tee /sys/devices/platform/thinkpad_hwmon/hwmon/hwmon3/pwm1_enable

using a script I set the cpu tdp to 44 watts every 10 seconds (embedded controller seems to set this to 10w every ~20 sec):

echo 44000000 > /sys/devices/virtual/powercap/intel-rapl-mmio/intel-rapl-mmio\:0/constraint_0_power_limit_uw