The fix I described before stopped working/ only works intermittently. However, installing Tiny10 on it somehow lets it run at full speed out of the box with no obvious BIOS setting or Throttlestop needed.

I bypassed this very easily by disabling turbo-boost and virtualization in the BIOS. Not sure which setting did the trick but no software was needed after this to run at 2.0 Ghz powered by a 20v USB C adapter. To go above 2.0, I used ThrottleStop.

No good brands make these, try out a few generics and pick the best