pxx hosted on a second platform

"pxx should run under linux/bsd/minix/gnu/windows/wasm 'kernels' ... and run a minimal system with compiler."

Hosted, not cross-emitted — the distinction is the whole umbrella

We already emit code for many targets. This umbrella is about the compiler running there: pxx on the box, compiling itself, reaching its own fixedpoint. make compiler/pascal26 proves that property on Linux/x86-64 every twelve seconds; it proves nothing about any other kernel.

The empty cells are the finding

OpenBSD has two tickets. Minix 2, Minix 3, GNU and Windows have essentially none — and that is not a gap in the backlog, it is an accurate report that nobody has attempted them. An umbrella with no blockers says unattempted, which is exactly what a 400-ticket flat backlog could never say.

Full goal: devdocs/dev/the-goal-cross-cross.md.