Huawei can just do what Apple does and get an ARM ISA license and design their own ARM compatible processor core.
I doubt that would have any US content to get banned.
The main problem with ARM is that NVIDIA is going to acquire it and more BS will happen for sure.
I think RISC-V would be an interesting choice but the problem with that is binary compatibility with existing applications. Intel tried for years to compete against ARM in the smartphone sector and even paid Lenovo to use their chips but because running Android applications on x86 required binary dynamic translation from ARM it just wasn't competitive. Of course if Huawei forces application developers to recompile their applications to Harmony OS on that architecture that would solve that problem but porting software a lot of times isn't just as easy as that. As Intel discovered also.
You have no clue of what you are talking about. Android apps are written in Java and are run on top of JVM, processor agnostic. Intel failed in the phone business because its processors takes up too much power.