参考に、boards.txtの一部です

lardu_328e.name= WAVGAT NANO 3.0
lardu_328e.upload.tool=avrdude
lardu_328e.upload.protocol=arduino
lardu_328e.upload.maximum_size=29696
lardu_328e.upload.speed=57600
lardu_328e.bootloader.tool=avrdude
lardu_328e.bootloader.high_fuses=0xff
lardu_328e.bootloader.low_fuses=0xff
lardu_328e.bootloader.extended_fuses=0x07
lardu_328e.bootloader.path=lgt8fx8e
lardu_328e.bootloader.file=lgt8fx8e\optiboot_lgt8f328d.hex
lardu_328e.bootloader.unlock_bits=0x3f
lardu_328e.bootloader.lock_bits=0x3f
lardu_328e.build.mcu=atmega328p
lardu_328e.build.f_cpu=16000000L
lardu_328e.build.core=lgt8f
lardu_328e.build.variant=lgt8fx8e
lardu_328e.build.board=AVR_LARDU_328E