The Hazard 3 is basically a hobby project of Luke Wren, a Raspberry Pi Employee. He's contiuing to evolve it further, but I don't think it's ready for a full replacement of the Cortex-M yet, especially in regards to the Security Features.
The source code is all from Luke Wren and I don't think other cores use the source code directly, but improvements to test harnesses or general implementation patterns as well as better software support help other cores: https://github.com/Wren6991/Hazard3
For the SoCs I would expect to see an off-the-shelf Risc-V core (certainly no Hazard3 as the main CPU), but we'll see.
The source code is all from Luke Wren and I don't think other cores use the source code directly, but improvements to test harnesses or general implementation patterns as well as better software support help other cores: https://github.com/Wren6991/Hazard3
For the SoCs I would expect to see an off-the-shelf Risc-V core (certainly no Hazard3 as the main CPU), but we'll see.