The Hyperflex M5 servers are designed to have either a local installer, or Intersight installer connect and configure the servers including boot order.
Hyperflex converged nodes are not configured for single node redundant storage (i.e. no raid controller), and will contain a number of jbod mode disks. ESXi will see the individual disks (i.e. 6 1TB disks), and cannot provide any redundancy. If this is just for a lab or test box then it shouldn't present a problem. NOT something you want production running on.
HX M5 servers ship with a M.2 SSD that will need a boot order entry created (sata , see picture below).
Also, please keep in mind that retasking an appliance sold with specific Hyperflex config, part IDs, and contracts, can create some support complications (hardware itself will always be supported while under warranty or contract).