Product : Microsoft, HyperV/2019, DataCenter
Feature : Boot From SAN, Storage, Network and Storage
Content Owner:  Roman Macek
Summary
Yes (iSCSI, diskless, FC)
Details
(no major updates with WS2019)

Booting from SAN is supported for iSCSI and FC
In Server 2012 the iSCSI Software Target capabilities were enhanced to support diskless network boot capabilities (you can use a single operating system image to start many diskless computers).
Comment: The new virtual Fibre Channel function is not intended to be a host boot option, rather than a means to provide FC attachment directly to virtual machines.