Presumably you have access to a windows IoT machine? Did you try it? Running it yourself is by far the best way to verify if any technology matches for your use case.
With regards to official support... I'm fairly sure Windows IoT is not an officially supported/tested platform. It might "just work" by virtue of being Windows, probably worth giving it a shot.
Also, Compose for Desktop is open source. Even if it doesn't work out of the box, it's probably just a matter of recompiling the Compose binaries for your device. Would require some amount of leg work, but almost certainly doable if you're so inclined. The dependencies (eg. Skia) compile on virtually every platform from Android to iOS to Linux, Mac, Windows, and even WebAssembly in the browser, so compiling for Windows IoT should be very doable if you have such a machine.