ARM (aarch_64):
#SVE2 Using a phone as a dev board, you're good to go. Latest flagship Samsung, OnePlus phones feature SVE2.
#SME Not accessible yet. Maybe we'll see dev boards, but for now it's [redacted] only.

RISC-V:
#RISCVV: Prelaunch spec Dev boards exist, but not much exists with the 1.0 (or higher) spec implemented in hardware. #HorseCreek from Intel+SiFive is supposed to be available this summer in the HiFive Pro P550
#RISCVM: FPGA prototyping only, spec is WIP

Use an FPGA ¯\_(ツ)_/¯