Testing the user agent is set/ Postman/ proxy

Basics newbie question/stupid question .
Also, not HTTPS. I want to inspect the user agent string sent by a native app making a HTTP GET request. the native app runs on Windows/linux/macos , but for simplicity I want to run it on Windows. It makes HTTPS requests, but I’m forcing the native app to make HTTP requests to let me test with a local webserver I spin up on the same computer.
I thought that postman would be able to capture all traffic to port 8000 (I’m running a basic webserver on localhost.) So I installed the postman “Agent” and installed the postman “App”, so I’m not installing a browser extension at all, since the app under test is a native app and it does NOT have postman integration. What I’m trying to do should not work I assume? I could simply install wireshark, but that feels a bit OTT , or is it the only way to capture local traffic?

Yeah - you can probably achieve it by running the traffic through a proxy such as Fiddler, Burp or Charles. Not sure how to set it up with a native Windows app, I have experience only with backend microservices and there it was super simple - when running the service locally, just set the proxy’s address in your environment variables.
Alternatively, you could check the user agent string in your backend logs, if you have access to those (edit: just realised you would have access to them since you’re running the server locally - so it’s just about whether the server is logging the agent string into stdout)