Unable to see any output in the Serial monitor about megacore HOT 2 CLOSED

I knew I am missing out something here.

So, I can upload programs via TinyISP but to check serial monitor, I will have to use the other port.

Got it.
Sorry about the false flag.

from megacore.

The hardware serial works just fine,, I've used it many times. It's a) something wrong with your hardware setup, og b) something wrong with your code.

Connect your USB to serial adapter as shown in the minimal setup in the README. I think you'll have to unplug your programmer, since the hardware UART and the programming lines share the same pins (PE0 and PE1).

Try uploading a simple sketch like tha AnalogReadSerial. Remember that the TX pin on the microcontroller goes to the RX pin on the USB to serial adapter and vice versa

from megacore.