It sounds like clang running on the RPi 1 generates code that doesn't run. Usually compilers default to targeting whatever ISA it's running on but that doesn't seem to be the case here.
Current docs about this option:
> LLVM target to use for code generation when no target is explicitly specified. It defaults to “host”, meaning that it shall pick the architecture of the machine where LLVM is being built. If you are building a cross-compiler, set it to the target triple of your desired architecture.
89luca89/distrobox: https://github.com/89luca89/distrobox #quick-start
89luca89/distrobox/blob/main/docs/useful_tips.md#using-a-different-architecture: https://github.com/89luca89/distrobox/blob/main/docs/useful_...
lukechilds/dockerpi: https://github.com/lukechilds/dockerpi : RPi 1, (2,3,) in QEMU emulating ARM64 on x86_64
E.g. the Fedora Silverblue rpm-ostree distro has "toolbox" by default because most everything should be in a container
containers/toolbox: https://github.com/containers/toolbox
From https://containertoolbx.org/distros/ :
> Distro support: By default, Toolbx creates the container using an OCI image called `<ID>-toolbox:<VERSION-ID>`, where <ID> and <VERSION-ID> are taken from the host’s `/usr/lib/os-release`. For example, the default image on a Fedora 36 host would be `fedora-toolbox:36`.
> This default can be overridden by the `--image` option in `toolbox create`, but operating system distributors should provide an adequately configured default image to ensure a smooth user experience.
The compiler arch flags might should be correctly specified in a "toolbox" container used for cross-compilation, too.
There are default gcc and/or clang compiler flags in distros' default build tools; e.g. `make` specifies additional default compiler flags (that e.g. cmake, ninja, gn, or bazel/buck/pants may not also specify for you).