The P&W PT6, which is probably the most common turboprop/turboshaft engine in the world, has a maximum continuous EGT of ~600°C and maximum instantaneous of 760°C.
(note: the respective document for a regular PT6 doesn't list the EGT, but only the inter-turbine temperature, ITT, which is generally used to manage the PT6 engine. Since the PT6T has the same parts, just twice, the same ITT will result in the same EGT.)
Since EGT is the terminal temperature, after all the turbine stages, it's not going to drop much while going into the exhaust. Plus, consider a slight permitted overtemperature.
Generally, if you're installing it in your plane, it's best to use materials that can handle at least 760°C for 30 seconds (where the engine might still remain in the B-area, safe to fly after inspection) and 650°C continuously (might be pushed there in a OEI contingency), with 550-600°C typical service.
This is still titanium range, but calling for high-temperature alloys such as 1100, rather than basic structural Ti-6Al-4V. Any factory exhaust will be designed for appropriate temperature.