UEFI HTTP Boot clarity?

I'm interested in learning more about UEFI HTTPBoot and setting it up for my LAN as a netboot option, but the details are notably sparse. The best docs I've found are [Suse Docs](https://documentation.suse.com/sles/15-SP2/html/SLES-all/cha-deployment-prep-uefi-httpboot.html) for configuring an HTTP Boot server, but it's lacking some information I'm wondering about. I use PFSense as my DHCP/DNS server. According to [this blog](https://mrguitar.net/?p=2393) , the option for HTTP boot in PFSense became available in 2.6, which is a pretty recent release. According to the blog post, PFSense must be configured with a specialty option to get this to work: vendor-class-identifier “HTTPClient” with a "Number" of 60. There's very little information about the boot process or requirements of the Network Boot Program (NBP), or the process to prep the payload for netboot. Have several questions: * Can any linux distro that supports UEFI (and has a *.efi file) be pointed to for HTTP Boot? * What is the process to prep the NBP? Extract a given distro's ISO contents to any HTTP static server and point to the *.efi file in the URL? * It seems once the EFI file is loaded, a bootloader is initiated? Will any bootloader work, or does it need to be something that specifically supports HTTPBoot? How is the bootloader configured such that the *.efi or some other process understands to launch that specific bootloader? * Is the root file system specified as just the path relative to the host in the URI file? * Once I have a bootloader configured, if I wanted to have several different available distros, do I just need to configure them accordingly in the bootloader config, and I can just pick one of the *.efi files to launch it? * What is the vendor-class-identifier option, and the "Number" associated with it?