rEFInd can automatically detect linux, Windows, and mac partitions and boot them. You could just install it to a usb stick and use it whenever necessary.
That's a very neat tool! I'm kind of turned away by this though:
> Warning: Your kernel and initramfs must reside on a file system that rEFInd can read.
Can it boot fully-encrypted disks (by chainloading GRUB, for example)?
What you mentioned is rEFInd’s auto detect feature which by design doesn’t work with encrypted disks. rEFInd will automatically detect other .efi binaries so you can just install your other bootloaders alongside rEFInd, make rEFInd the default and chainload into your other bootloaders when you need to boot an encrypted disk.
I have a setup where I moved /boot of the encrypted luks partition to the esp and boot from there using a custom entry in rEFInd
