INDMATEC is a German company that sells PEEK filament. The specifications say it needs 343C. Would hexagon be able to reach(and keep) this temperature?
The Hexagon thermistor is only useful up to 300C. To go hotter than that you’d need to explore using a thermocouple for the temperature sensing portion.
Is the Hotend capable of exceeding 300°C?
Would an E3D V6 PT100 upgrade kit enable me to theoretically print PEEK?
Since that’s a thermocouple, yes. You might also have to look at thermally isolating the cold end a bit more, maybe a layer of ceramic tape between them and some additional protection around the main frame so the ABS doesn’t start falling off mid print.