If you’re using wire shark you don’t also need mitm proxy. Mitmproxy is similar to fiddler/burpsuite in that they are high level traffic capturing tools whereas the with Wireshark you can inspect the actual TCP packets. It takes more setup as you’ve seen
Certainly true if the target application is running on the same host as Wireshark. But mitmproxy is very helpful when the device or application isn't fully under your control, for example if you can't set a proxy.
Mitmproxy also has a few features which make it a lot easier to use than wireshark alone, even if the aim is only to inspect TLS traffic. Including the wireguard server mode or transparent proxying for example.
Another approach is to route things through a managed switch and use port mirroring to get a the traffic. More expensive or not, maybe dependend on whether you have managed switches in the network or not. Less intrusive though.
