for Chinese devices, there's no way to disable them.
the difference is, for Windows, having Bing on start was a feature (although a bad one). for Chinese devices, you just get ads - you're stuck with ads while changing your brightness.
And as other commenters have pointed out, lots of budget phones and hardware jam ads all over the place.
Premium hardware too (hello Smart TVs)
Uh can you stop spreading misinformation? Try google "disable xiaomi ads" it takes you like 5 minutes to make all ads gone on MIUI or HyperOS. Sure the opt-out buttons were hidden deep behind menus for maximizing profit.
But be warned, in certain countries you are getting a modified ROM from your local re-seller, in that case some ads can't be disabled and they are not from Xiaomi. The only solution is to flash your ROM to the official releases.
While they do include MS services in their advertising it's way more than that. They include a bunch of other crap, including hardware offerings like trying to sell you XBox controllers in popups near the taskbar. They advertise Candy Crush, Instagram, Adobe Express, etc, as listed apps "preinstalled" in Windows. They push clickbait MSN articles (ads) for games, travel, and buying guides in the search button of the taskbar that is enabled by default. They then push those in a widget popover panel too. They make Edge the default browser out of the box (and are relentless about getting you to switch if you change it) and Edge itself then shoves ads in your face with default bookmarks like Ebay and Netflix and Walmart and featured content. IIRC even things like their Maps, Weather, and Photos apps also had web advertising placements.
There's probably more but I can't bear to use Windows more than minimally necessary so I've probably missed a bunch.