Here's data from differential scanning calorimetry (DSC) for ABS and PETG. These are amorphous plastics with no true melting point - they just gradually get less viscous with temperature. That's one reason
How To Properly 3D Print When Working With PETG Filament
TG (a) and DTG (b) curves for PETG-block-PTMO copolymers under air... | Download Scientific Diagram
Glass Transition Temperatures of PLA & PETG | All3DP
Glass Transition Temperatures of PLA & PETG | All3DP
PETG Glass Transition Temperature | A Ultimate Guide - PlasticRanger