If it's at the same spot in the pedal stroke, I would look to the bottom bracket or pedals first.
If the pedal threads are loose, it's pretty obvious. Most of us just screw 'em in, no torque wrench, and that works fine. They don't have to be super tight.
If pedals are old, they could have worn bearings. If they're new, they could be defective, but that's unlikely. Even more unlikely that BOTH would be worn or defective!
It's possible to get sounds from the saddle, wheels, etc, that happen in time with the pedal stroke because the bike/saddle is being rocked one way or the other with each stroke or the frame is flexing with each stroke.
Check quick release to make sure it's not loose and letting the wheel shift as the bike rocks.
If my front wheel makes a noise, it sounds like it's coming from the front. If my back wheel makes a noise, it still sounds like it's coming from the front. So I've learned not to trust that. Sometimes, having somebody ride beside you can help pinpoint a noise better than you can riding.
There's times when a good bike shop comes in hand, cause they've seen it all before.
__________________
"be careful this rando stuff is addictive and dan's the 'pusher'."