Platform: lgt8f
=====================================================================
ID                MCU         Frequency  Flash  RAM  Name
----------------  ----------  ---------  -----  ---  ----------------
LGT8F328P         ATMEGA328P  32MHz      29KB   2KB  LGT8F328P
lgt8f328p-LQFP48  ATMEGA328P  32MHz      29KB   2KB  LGT8F328P-LQFP48
LGT8F328P-SSOP20  ATMEGA328P  32MHz      29KB   2KB  LGT8F328P-SSOP20
lgt8f328ps20      ATMEGA328P  32MHz      29KB   2KB  LGT8F328P-SSOP20

$ vi src/serial.ino
void setup() {
  Serial.begin(9600);
}
 
void loop() {
  if (Serial.available() > 0) {
    char c = Serial.read();
    Serial.println((char)c);
  }
}

$ vi platformio.ini
[env:LGT8F328P]
platform = lgt8f
board = LGT8F328P
framework = arduino

lib_deps =
  6214
  31
  13
  12

board_build.f_cpu=32000000L
;internal clock
board_build.clock_source=1

【Seeeduino XIAO】
#define TFT_CS    1
#define TFT_RST   2
#define TFT_DC    3
#define TFT_SCLK  8
#define TFT_MOSI 10

【ALPHA 8F328P-U】
#define TFT_CS    1
#define TFT_RST   2
#define TFT_DC    3
#define TFT_SCLK SCK
#define TFT_MOSI MOSI

#include <Adafruit_AHTX0.h>
#include <Adafruit_GFX.h>
#include <Adafruit_ST7735.h>
#include <SPI.h>

#define TFT_CS    1
#define TFT_RST   2
#define TFT_DC    3
#define TFT_SCLK SCK
#define TFT_MOSI MOSI

#define BLACK   ST7735_WHITE
#define CYAN    ST7735_BLUE
#define ORANGE  ST7735_ORANGE

Adafruit_AHTX0  aht;
Adafruit_ST7735 tft = Adafruit_ST7735(TFT_CS, TFT_DC, TFT_MOSI,
TFT_SCLK, TFT_RST);

void setup(void) {

  if (! aht.begin()) {
    Serial.println("Could not find AHT? Check wiring");
    while (1) delay(10);
  }
  tft.initR(INITR_MINI160x80);

  tft.setTextWrap(false);
  tft.setRotation(3);
}

void loop() {

  sensors_event_t humidity, temp;
  aht.getEvent(&humidity, &temp);

  tft.fillScreen(BLACK);
  tft.setCursor(5, 30);
  tft.setTextSize(2);

  tft.setTextColor(ORANGE);
  tft.print(temp.temperature);
  tft.print("C ");

  tft.setTextColor(CYAN);
  tft.print(humidity.relative_humidity);
  tft.println("%");

  delay(1000);
}