1. Yes, that's exactly right. It installs a GRUB version compiled into a PE executable, typically. 2. Boot sector support requires UEFI CSM support, which most

1. Yes, that's exactly right. It installs a GRUB version compiled into a PE executable, typically. 2. Boot sector support requires UEFI CSM support, which most PCs have (but ARM based devices and Intel Macs don't). With the deprecation of 32-bit architectures in a lot of operating systems, some vendors also started dropping CSM support in some devices, but most devices still ship with CSM either enabled by default or as an option in the settings.