Unfortunately, the upstream zig toolchain (LLVM codegen) does not support the Xtensa architecture (opaque CPU features), but it is possible to use riscv32 for esp32 from the C2/C3/C6, H2 and the new P4 release.
I'm currently working on a fork of the zig toolchain with espressif-LLVM to support Xtensa.[1]
It is now possible to test with esp-idf instead of microzig for baremetal (Blink) yet.
Yeah I remember reading about it's relation to LLVM issues etc. I also think there was another (languishing) fork of the entire zig repo which had some support for Xtensa which I couldn't find at the time, but I found it.
Edit: I see you are the same kassane from the GitHub thread. Thank you for your efforts on Xtensa support! Would be great to have it out-of-the-box at some point.
I have been following https://github.com/ziglang/zig/issues/5467 for a while and progress seemed to have slowed significantly