Over the last few years, he has:

* Taken the last public source code snapshot of QNX, version 6.4, got it building again and then ported this 32-bit kernel to 64-bit RISC-V

* Built a new RISC-V based IBM-PC-like personal computer from scratch on an FPGA

* Built a little-endian IBM S/360-like mainframe on the same FPGA

* Built a new RISC-V RTOS inspired by QNX but FOSS, with 2 alternate kernels: his own multiprocessor microkernel, or seL4.

Which is you see too much to fit into an HN title.