In vSphere 7.0 Update 2, an enhancement was made to the Virtual Machine's UEFI firmware called VirtualEFI that would enable ESXi to run in a VM (Nested ESXi) and perform an HTTP Boot given the ESXi bootloader URL without requiring any traditional PXE infrastructure.
This was especially useful for anyone testing or developing ESXi automation for use with ESXi Kickstart, where you can quickly prototype your automation without additional infrastructure dependencies and once the automation has been vetted, you can then leverage that exact same automation in your physical ESXi provisioning infrastructure.
The original solution had only supported HTTP and I recently came to learn that we can now also support HTTPS in vSphere 8!