USB installer not showing up in the mac boot menu

I have a Macbook pro 15" from mid 2015, and after creating the mac os sonoma installer and installing open core on it, when I reboot to the boot menu, it doesn't show up. Why is this? I have not found any one else having this problem when installing open core, so why am I the only one (or the only few) that ran into this issue? I don't have a big enough usb flash drive, so I just use a 64gb sd card on a usb sd card reader. Could that be the reason? That might be a possibility but I don't see a reason why it would be that because I've used sd card + usb sd card reader to create windows installers and those just work fine. Do I have to actually get a big enough usb flash drive?

submitted by /u/entryjyt
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