Combine with your other post: for multiboot (running each OS on bare metal), Win 10 has to be installed first, as it insists it is the only thing worthy of being on the laptop and will destroy the GRUB boot sector.

Partitions have changed, but that is EUFI thing; the changes are not limited to SSDs. The old 4 partition limit is gone which does make installing multiple OSes side by side much easier.

Windows 10 can shrink itself, but even fresh out of the box, it will not go much below ~120 GB.

GRUB does not mean a SystemD free distro. Devuan is dedicated SystemD free and is quite usable (the unstable version is my daily driver on similar hardware. Unstable is needed to get around some wrinkles related to IRQ/GPIO differences with the new i7 CPUs. It primarily impacts the operation of some i2c bus trackpads.)

For VM operations, I've used the open source Xen hypervisor + QEMU without issues, but that was on server hardware and the guest OS as Windows Server (up to 2012.) If you want to try that, you can set up a classic dual boot with Win 10 native on one side (assuming that is what came with the laptop) and a Xen kernel on the other. The remaining drive space can be configured as "harddrives" to the guest OSes to do with as they please. (But as Box mentioned, Win 10 Home may not work, and for any edition of Windows, you'll need a non-OEM license key.)

The biggest immediate hurdle will probably be to get around the UEFI SecureBoot restrictions. Debian has a signed installer but I haven't looked into how that translates to Devuan.