You could take advantage of all of the ACPI-aware buses supporting the ACPI handle ivar to make this a shared function across the various ACPI-aware buses. Something like:

int
acpi_get_device_path(device_t bus, device_t child, const char *locator, struct sbuf *sb)
{
     if (strcmp(locator, BUS_LOCATOR_ACPI) == 0) {
         ACPI_HANDLE *handle = acpi_get_handle(child);

         if (handle != NULL)
              sbuf_printf(sb, "%s", acpi_name(handle);
         return (0);
    }

    return (bus_generic_get_device_path(bus, child, locator, sb));
}

I think all of the buses you patch here could then just reuse that directly (some of them might later have to still grow a driver-specific method for UEFI, but that could at least call this shared routine after handling UEFI).

Maybe sort these somehow, e.g. alphabetically? Probably make the first commit that adds UEFI follow whatever convention you decide to follow?

sure.