I'm going through a process of elimination.
The noise initially presented itself as a creaking/clicking noise and the timing correlated with the pedal stroke at a certain position under stress (hard pedaling).
I removed the bottom bracket, cleaned, greased and reinstalled. Then I noticed the left pedal was not rotating very freely - disassembled, greased and reinstalled.
I retorqued the stem and steerer cap bolts.

The hard creaking sound has disappeared. But the clicking sound is persistent and more of a click than a creak.

The cable housing and cables were replaced about 2500-3000 miles ago and look clean.

The clicking can be reproduced under hard pedaling or by putting pressure on the handlebar while moving and turning the bar side to side.

Sound seems to come from the headtube area. Could be the front hub instead ?

I cannot replicate the sound with the bike on the stand