Help me understand this better.

From what I have read online, since arm just licenses their ISA and each vendor’s CPU design can differ vastly from one another unlike x86 which is standard and only between amd and Intel. So the Linux support is hit or miss for arm CPUs and is dependent on vendor.

How is RISC-V better at this?. Now since it is open source, there may not be even some standard ISA like arm-v8. Isn’t it even fragmented and harder to support all different type CPUs?