You can get GC logs without debugger. But why do you need them? Debugging lags is not really a stuff that power users should do.
> GC or not, Android or iOS, all these systems should have basic self-monitoring and logging features *built-in* producing clear, power-user readable reports of all events like "ran out of memory, terminated X while Y was using 100M" and "ran GC for 2 seconds", etc.
Android has something like it, it can estimate the power use by application. You can use various apps to view these stats.