Hey!
I am using STM32F407VET6 board: https://stm32-base.org/boards/STM32F407VET6-STM32-F4VE-V2.0
This board has a 16-bit FSMC interface.
This interface makes it easier to work with the TFT display and significantly speed up drawing on the display.
I found the only library that works with this interface: https://github.com/stevstrong/Adafruit_TFTLCD_16bit_STM32
The library is running and the display shows an image.
But this library only works with Arduino_STM32 core: https://github.com/rogerclarkmelbourne/Arduino_STM32
But this is not a complete core. Support for F407 series microcontrollers is very limited. Many functions do not work correctly or do not work at all.
Arduino_Core_STM32 core is very good: https://github.com/stm32duino/Arduino_Core_STM32
But I did not find support for TFT displays with FSMC in it.
Can you modify the library to support 16-bit displays with FSMC interface?

I've got an Open-Smart 16 pin ILI9488 3.5inch 320x480 "expansion module" from e-bay.
https://www.ebay.com/itm/3-5inch-TFT-Board-Expansion-Module-LCD-Touch-Screen-For-R3-Nano-Mega2560-Hot/233641518844?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
I hooked it up to a Black Pill STM32F411CE.
I looked at the .cpp and saw it briefly mentioned the ILI9488 but I'm not sure if it supports it. (I don't really understand the code.) I'm probably doing something wrong.
I ran the GraphicsTest_320x480_SMT32.ino and it looks like it is communicating with each other but there is nothing on the tft screen. In the Serial Monitor I am seeing this;

Arduino-STM32-8bitTFT
readReg16(0)=0x0
readReg32(A1)=0x3093
readReg40(BF)=0x9393
readReg32(D4)=0x0
readReg40(EF)=0x0
readReg32(FE)=0x0
readReg32(04)=0x548066
readReg32(D3)=0x9488
Device ID: 0x9488
Width: 320
Height: 480
Benchmark Time (microseconds)
Screen fill 2115372
Text 77333
Lines 962493
Horiz/Vert Lines 182033
Rectangles (outline) 108761
Rectangles (filled) 5310698
Circles (filled) 1258549
Circles (outline) 411223
Triangles (outline) 194504
Triangles (filled) 1925425
Rounded rects (outline) 197330
Rounded rects (filled) 5885654
Done!

Thank you in advance for any help you could give me.
Doug

Code in example doesn't work on stm32f401ccu6 v3.0 + display ILI9486 with core from ST

After the code LCD_ID_Reader.ino is executed, i.e. the pins are connected correctly, the ID is readable.

reg(0x00D3) 00 00 94 86.ILI9341, ILI9488

I connected black pill to display as below:

#define TFT_RD         LL_GPIO_PIN_0 // Px0
#define TFT_WR         LL_GPIO_PIN_1 // Px1
#define TFT_RS         LL_GPIO_PIN_5 // Px5
#define TFT_CS         LL_GPIO_PIN_6 // Px6
#define TFT_RST        LL_GPIO_PIN_7 // Px7

White screen.

I connected black pill to display as below:

#define TFT_RD         LL_GPIO_PIN_3 // Px3
#define TFT_WR         LL_GPIO_PIN_4 // Px4
#define TFT_RS         LL_GPIO_PIN_5 // Px5
#define TFT_CS         LL_GPIO_PIN_6 // Px6
#define TFT_RST        LL_GPIO_PIN_7 // Px7

Screen white also...
Same hardware work good with TFT_eSPI and pins as below:

// common "MCUfriend" shields
#define TFT_CS   PB8  // Chip select control pin
#define TFT_DC   PB7  // Data Command control pin
#define TFT_RST  PB9  // Reset pin

#define TFT_WR   PB6  // Write strobe control pin 
#define TFT_RD   PB0  // Read pin

#define TFT_D0   PA0  // 8 bit parallel bus to TFT
#define TFT_D1   PA1
#define TFT_D2   PA2
#define TFT_D3   PA3
#define TFT_D4   PA4
#define TFT_D5   PA5
#define TFT_D6   PA6
#define TFT_D7   PA7

I changed in the library TFT_eSPI pins as for the library and everything worked.

#define TFT_RD   PB0  // Read pin
#define TFT_WR   PB1  // Write strobe control pin 
#define TFT_DC   PB5  // RS/CD - Data Command control pin
#define TFT_CS   PB6  // Chip select control pin
#define TFT_RST  PB7  // Reset pin

#define TFT_D0   PA0  // 8 bit parallel bus to TFT
#define TFT_D1   PA1
#define TFT_D2   PA2
#define TFT_D3   PA3
#define TFT_D4   PA4
#define TFT_D5   PA5
#define TFT_D6   PA6
#define TFT_D7   PA7

When I changed the pins in various options for the library Arduino-STM32-8bitTFT nothing worked and the screen was still white.
You write that the library works with ILI9486, but I did not find initialization in the code, for ILI9481 only:
case 0x9481: //ILI9481

I have an ILI9225 Parallel TFT 2.0" display with the following wiring, but i only see white screen with STM32F401 MCU.

D0-D7 -> PA0->PA7, TFT_CS -> PB8, TFT_DC -> PB5, TFT_RST -> PB9, TFT_WR -> PB1, TFT_RD -> PB0

I use this config:

#define TFT_DATA GPIOA
#define TFT_PORT PORT_LOW
#define TFT_D0 LL_GPIO_PIN_0
#define TFT_D1 LL_GPIO_PIN_1
#define TFT_D2 LL_GPIO_PIN_2
#define TFT_D3 LL_GPIO_PIN_3
#define TFT_D4 LL_GPIO_PIN_4
#define TFT_D5 LL_GPIO_PIN_5
#define TFT_D6 LL_GPIO_PIN_6
#define TFT_D7 LL_GPIO_PIN_7

#define TFT_RD LL_GPIO_PIN_0
#define TFT_WR LL_GPIO_PIN_1
#define TFT_RS LL_GPIO_PIN_5
#define TFT_CS LL_GPIO_PIN_8
#define TFT_RST LL_GPIO_PIN_9

An ILI9341 display works fine with the same setup.
Is the ILI9225 display not supported?

(The ILI9225 display also works with the TFT_eSPI library)

readReg40(BF)=0x0
readReg32(D4)=0x0
readReg40(EF)=0x1818
readReg32(FE)=0x0
readReg32(04)=0x0
readReg32(D3)=0x0
readReg16(0)=0x9226
Device ID: 0x9226
Width: 176
Height: 220

connet lcd data pin to a GPIO pot 0~7pin，then change the function STM32_TFT_8bit::write8 to:

void STM32_TFT_8bit::write8(uint8_t bytes) {
    TFT_DATA->ODR = bytes;
}

write speed will more fast, here is my benchmark result, left is after change, my board is F411CEU6