@gerb45 I did a little bit of testing with Raspberry Pi OS on a Pi Zero 2w and a PowerBlock. This should work for a RPi4. You can add the following to config.txt to emulate the driver. (This way you don't have to worry about startup scripts.)

dtoverlay=gpio-poweroff,gpiopin=17,active_low=1,inactive_delay_ms=0 dtoverlay=gpio-shutdown,gpio_pin=18,active_low=0,gpio_pull=down

It seems to work identical, except that it indicates boot finished before boot actually finished. (Can anyone confirm this please?)

ok i re install advemame ,play with the video options and cotton 2,groove on fight are ok.

The main folders you want to back up are:

/home/pi/RetroPie (ROMs, BIOS files, splash screens) /opt/retropie/configs (configs for RetroArch, EmulationStation, also your scraped game library) /etc/emulationstation(custom themes as well as the systems ES has access to)

The RetroPie documentation has info on how to copy files. WinSCP or Filezilla are probably the easiest programs to use.

Copy those over from the 3B to the 4, and you should be fine. Note: after you flash the image onto your RPi4, you'll need to boot up with it for RetroPie to finish installing, then you can turn it off and start copying.