This project uses the released v3.6c version of the Larduino Arduino core (https://github.com/LGTMCU/Larduino_HSP/files/3333048/Larduino_HSP_v3.6c.zip).
This is not the same as the core version in the Larduino_HSP repository, for some reason (was never updated).
See https://github.com/maxgerhardt/larduino-pio/tree/master/boards for the list of boards. They are copies of the ones available in Arduino IDE, defined in the boards.txt.
For example for the "Larduino w/ LGT8F328D-SSOP20" board, choose board = lardu_328s in the platformio.ini. See the boards folder for all boards.
If you want to run at 32MHz, uncomment the line
;board_build.f_cpu = 320000000L
in the platformio.ini