Template and query rendering is indeed delegated to the server, except when you run in Sync mode. So if you want to run a debugger, that may be the way to do that. Honestly, I don’t use debuggers myself (yikes), I’m more of a console.log debuggers.
On that topic, console.log should work perfectly fine also for this purpose, except of course that since queries and templates are executed on the server, console.logs will also appear on the server log (standard output) instead of in the browser. So perhaps you were looking in the wrong place?