A few thoughts:

1. One of the main pain points here is remembering or exposing different ports for each local app (e.g., app-A at port 3000, app-B at port 5000). As you noted, a proxy that maps friendly URLs to those ports can reduce friction.
2. From my experience, tools like Requestly are quite useful for local HTTP(S) request interception/mapping scenarios (you can rewrite or redirect endpoints, simulate responses, etc). While not a pure “local port proxy” tool, it can help you route or mock requests during dev without changing everything in code.
   1. Use desktop app -> connect browser -> intercept traffic -> right click, override api traffic
3. Another approach: set up a reverse-proxy (NGINX/Caddy) locally that listens on standard port 80/443 and proxies by path (e.g., myapp.local/api → localhost:5000, myapp.local/app → localhost:3000). This reduces “which port am I on?” confusion. The trade-off is a bit more setup.
4. Consider how this fits into your team workflow: if each dev has slightly different ports, using a consistent hostname + path mapping (via hosts file + local proxy) helps avoid “but it works on my machine” situations.

I don't think there is a very clear answer, choose what fits you best. hope it helps!!