I was able to use Smokeless to successfully set 16GB UMA Frame Buffer as well! The main difference I noticed so far was being able to do some outpainting in InvokeAI, which previously always ran out of memory. I haven’t got a chance to try larger models or images yet.
However, what is strange is that I’m not seeing the boot entries you’re seeing, @Xal, either on the BIOS Boot Manager screen, or in the efibootmgr. Like you, I was using the Beta version, booting it from a FAT32-formatted USB. Not sure what we’re doing differently. 