@marcorudy keep in mind that on any modern x86_64 system you will SHARE you windows-made EFI partition with Linux. If you use 2nd SSD you will still get one EFI partition.

Using grub to select windows/linux is not really useful anymore. You must use bios to select for proper TPM measurements.

If you go with 2 SSD then REMOVE the windows SSD during installation and then put both back. You will get two EFI partitions and both disks will be fully independent.

Hope that helps!