(re: PinePhone Keyboard, ppkb) /etc/default/keyboard is ineffective to set xkbcommon model (and/or entire RMLVO/KcCGST)

RMLVO, KcCGST, what's that? See https://xkbcommon.org/doc/current/md_doc_user_configuration.html#autotoc_md15

Phosh/Phoc leverages [lib]xkbcommon (https://xkbcommon.org/), as I suspect many Wayland compositors/shells/environments do.

The PinePhone keyboard, being new and different, needs to be specified in order for the appropriate setup to function in alignment with the printing on the keys themselves; specifically, to enable the extra "alternate keys" on the top row (0-9, F1-F10, and the alternate keys, |\£€~`-=_+, and maybe Delete, and possibly "hidden" symbol on the Escape key 😉).

As per the documentation (https://xkbcommon.org/doc/current/group__context.html#envvars, https://xkbcommon.org/doc/current/structxkb__rule__names.html#a1c897b49b49c7cd495db4a424bd27265) libxkbcommon respects environment variables to set defaults, like XKB_DEFAULT_MODEL, falling back to a system default if otherwise not set. Debian uses /etc/default/keyboard to specify the system default, but this must not be plumbed to libxkbcommon correctly, as setting it is ineffective.

The goal of this issue is to investigate this situation and determine the appropriate change to resolve this situation about Mobian (and of course, Debian).