Is there something wrong with the shield, or something that has changed with the Arduino platform that makes the shield not work well anymore or something?
What do you suppose that the demand was for the board? What is the cost of making, stocking, and selling that few of anything? Compared to other things that do sell well, which would you continue supporting?
Read the circuitssthome link including the links to other pages. There are pictures of the shield and the mini board. There are instructions on moding the mini board for 5 VUSB.
The USB host shield library indicates ESP32 is supported.https://github.com/felis/USB_Host_Shield_2.0The shield is designed for 5V logic levels so use the mini board with ESP32 which is designed for 3.3V logic. Note cutting traces and soldering required.https://www.circuitsathome.com/arduino_usb_host_shield_projects/The library includes keyboard examples.
The following is a simpler device that might work for your application. I have never used so I cannot answer any questions about it.http://www.hobbytronics.co.uk/usb-host-keyboardNote the pro mini must operate using 3.3V logic levels to work with the USB host mini board. These two boards together appoximate the capabilities of the Hobbytronics device.The usb host mini has a SPI interface and the ESP32 has a SPI interface so there is no need for the pro mini or the hobbytronics device. But whatever is easiest for you.In the USBHIDBootKbd example, the following functions will be called when a USB keyboard key is pressed. OnKeyDown is called for regular keys and OnControlKeysChanged is called for shift key(shift, control, alt, GUI/Windows). Put your code to handle the keys inside one of these functions.Usb.Task() keeps checking the keyboard for key presses then calls one of the above functions when a key is pressed. There is no need for a Keyboard.read function.It does not help to post multiple messages all over the board all on the same topic.