MFA Delete protects against accidental/permanent deletions in versioned buckets using MFA, while Object Lock is no overwrite or delete for compliance, even against the root user in Compliance Mode.
FSx for NetApp ONTAP
Yes AWS FSx supports Linux/Unix, but only with FSx for Lustre
Fsx Lustre - when we need high-performance computing.
Fsx - It is for Windows File Server when we need SMB shares, Windows-native apps
No. They are only for Express One Zone storage class.