Easy steps so we can use debugger that you may not know. See below example with Next.js, chrome DevTools:

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Steps

Run this script, we can run development with debugger attached.

NODE_OPTIONS='--inspect' next dev

You will see these outputs:

Debugger listening on ws://127.0.0.1:9229/e8290eb3-2965-4718-8fb9-d47b56c94b5c
For help, see: https://nodejs.org/en/docs/inspector
   the --inspect option was detected, the Next.js router server should be inspected at port 9229.
  ▲ Next.js 14.2.10
  - Local:        http://localhost:3000
  - Environments: .env.development.local, .env

 ✓ Starting...
   automatically enabled Fast Refresh for 1 custom loader
 ✓ Ready in 1626ms
 ○ Compiling /api/contributions ...
 ✓ Compiled /api/contributions in 1053ms (804 modules)

In your browser, open DevTools in chrome or microsoft edge, you will see this.

Just add a breakpoint or put debugger on any line.

Start to run something with server actions. In my example, i went to my home page with api route running.

Reference links you may need to know more.