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.
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.
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.