The RetroPie RPI image is just a Raspi OS Lite installation, so as far as booting is the same as a Raspi OS image. Just write the image to the USB disc and boot from it. With any recent Pi4 revision, it should boot from USB automatically.
@mitu Yeah I figured that after. I think I couldn't run any commands, so I plugged it out.
I think I was testing to see if the hub worked on USB 2.0 a little bit before the error occured, so I've kept it in a USB 3.0 port. I've been testing for a while now and there don't seem to be any issues anymore. Hopefully, the problem won't come up again.
I'm not sure how that works or if the bootloder on the EEPROM supports booting an Android image directly. Does the image work if you boot it from the sdcard ?
I did some more tests and I guess I found out what was causing this problem. After cloning the sd card everything works fine until I copy my rom's to the ssd. I just attached the ssd with the usb adapter to my Ubuntu machine and copied everything there to get faster speeds. But it seems that this method changes something in the filesystem that then causes all sorts of problems when booting from the ssd.
I now simply copied the sd card to the ssd again to get a fresh start and then copied everything with SFTP and now everything seems to be running fine.
I just tried my MicroSD card into a USB 2.0 MicroSD card reader and booted into Retropie.
It's giving me faster speeds on 4K random read and write.
WTF?! LOL
Not really retropie based, but you could try Demul or nulldc. Just download the zip files, not the installer.
You probably have to reconfigure the bios and Iso folders each time you open it on a different device.
@madmodder123 Thank you! I will try this when I get home. Would something like Knoppix work as well? I think I'm going to try SSH first so I don't have to take the usb out of the Pi