TL;DR – skip to the emphasised parts.
I came across this question asking for instruction and explanation on
how to configure the EFI BIOS boot menu to contain an entry for each operating system on a multi-boot setup and
how to configure Grub so that it skips to Ubuntu right away (because we already made our choice at an earlier stage).
I'm sure the 2nd is on topic but what about the 1st? Afaik EFI BIOS configuration isn't something that's part of Ubuntu or can be controlled with Ubuntu. On top of that, there are heaps of wildly different EFI implementations out there depending on the mainboard. The question doesn't even mention which one.