That is not a valid path, because
/dev/sda1 is a file, not a directory. Also, the physical device is irrelevant here, because it will look for the directory
/boot/efi, regardless of what underlying device is mounted to that directory.
In essence, you don't even have to specify any parameters, other than for disabling the Reed-Solomon error codes ─
--no-rs-codes ─ because they're not needed in UEFI installations with a GPT partition table, but the default install in Manjaro leaves them enabled.
Everything else will be autodetected, based upon the contents of