It looks like the upcoming Linux 6.13 cycle will be adding RISC-V support for user-space pointer masking and tagged address ABI.
RISC-V pointer masking can be used for implementing memory tagging akin to the Arm Memory Tagging Extension (MTE) by way of ignoring various bits of the effective address on RISC-V platforms. Memory tagging can help with the memory safety state of user-space applications.