No issues! I followed a mash-up of this Windows/Ubuntu installation guide for the Framework and this guide to installing (Windows and) Ubuntu with LUKS encryption and LVM to set up a Windows install (with Windows EFI System Partition and the regular Windows partitions) and an Xubuntu install (with its own EFI partition which ends up as the default boot partition and can boot Xubuntu or Windows via GRUB, an unencrypted /boot partition, and a LUKS partition with root, swap, and home LVM logical volumes in it).
[Boring details follow, in case useful for anybody — but the guides linked above explain this more clearly.]
I first did the Windows install, leaving lots of space for Linux. Then I booted into the Xubuntu live session (“try xubuntu” from the installer media) and manually added the Linux partitions (second EFI, /boot, and LUKS-encrypted partition), made the decrypted equivalent of the LUKS partition an LVM physical volume, added it to a volume group, and and created the root, swap, and home partitions in that volume group. Then I launched the Xubuntu installer from the live session and did the install. Before rebooting, I had to chroot into the freshly installed system and add an /etc/crypttab to allow decrypting the LUKS partition at boot and rebuild the initrds. Somewhat to my surprise, everything worked after rebooting. 
And I can boot into Win 10 Pro or Xubuntu at will. (Haven’t yet tried starting one as a VM under the other, but I feel confident that will work.)