> platform fragmentation
RISC-V is addressing this issue quite directly. For things like desktops, laptops, SBCs and servers we have the RVA23 profile which defines quite specifically what features a chip must support to ensure code portability.
On top of this, there are platform specifications. For example, the server spec is about to finalize next month. It extends RVA23 which things like UEFI, SBI, and ACPI to ensure that your can take something like a Linux distro and easily install it on any RISC-V server, like you can in the world of x86-64.
> we have phones that are only good for landfill once their support lifetime is up
RISC-V will probably not solve that problem in general.
First, the ISA cannot really demand that your phone avoid a Broadcom wireless chip that requires proprietary firmware for example.
Also, the phone vendor can still lock down the devices to prevent running arbitrary code.
Thankfully, the RISC-V world is developing a culture of openness. If a company wants to create a fully “open” phone, they are quite likely to adopt RISC-V. And, because of RISC-V, even the SoC itself could be fully Open Source.
But your typical Android phone is not going to get more Open just because they contain a RISC-V CPU.