I just did some more research and aparently my intel was a bit outdatet (from arount 2020). The guide should still work, though booting from SSD should be working by default and does not require any eeprom-updates. So you can probably start with step 4.
Raspberry Pi4? Then yes, here’s a guide to update your bootloader:
https://www.raspberrystreet.com/learn/how-to-boot-raspberrypi-from-usb-ssd
For older models(Pi<4), no but kinda: Afaik oder models could only boot from SD-cards. But that only means the bootloader has to be on the SD-card. So you can copy everything but the bootpartition and change the entry in the /etc/fstab to the new root on the SSD.
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