Manufacturers will say they're not supporting W10 on their new laptops (i got this response from XMG for example which are top notch with support - even tho they've also said that W10 will most probably work with W11 drivers, Asus is not listing W10 as an option for drivers, etc - not to mention that starting with Intel series 12 CPUs, W11 is required for proper scheduling between P and E cores - but you know this all too well)
No official support and not actually functioning are quite distinct. Windows 10 and 11 drivers are usually identical, aside from the OS build info limitations in the .inf, and most drivers don't come from system integrators at all. A few OEMs have first-party-branded controllers, but by and large, when I'm installing drivers on an laptop, I'm getting them from Intel, AMD, MediaTek, Realtek, Qualcomm, Broadcom, ASMedia, etc...not whoever's logos are printed on the laptop itself.
As for scheduling on heterogeneous processors, Windows 11 still has some advantage here, but Windows 10's support in this regard has improved significantly, and both have nearly the same options to control between P and E cores in their power management profiles.
Of course, if the goal is simply to avoid creating a Microsoft Account, that can be done on Windows 11 with less work (it's one checkbox when making the installation media in Rufus, or a couple lines typed into command prompt otherwise) than getting Windows 10 to run flawlessly on a system that only officially supports Windows 11 (which is more tedious than difficult...mostly just looking up device ids to find compatible drivers).
