Tony Finch's blog

I dunno whether PAC on data is widespread, but it's in the architecture. This is a random research paper I found via google which describes a setup that uses the data part of the PAuth extension to protect pointers to operations tables (ie structs of function pointers) inside the Linux kernel. But my impression is that the general expectation would be that you use PAuth on code pointers and MemTag for data pointers.