I run a Xiaomi Air 13 with both an embedded Intel and a discrete Nvidia
graphics chipset.  I'd like to turn off the Nvidia chipset to save
battery power and avoid overheating (I live in a hot place).

Blacklisting the "nouveau" kernel module prevents the card from being
seen by the OS, but the card keeps draining power:

    (operating-system
     ;...
     (kernel-arguments '("modprobe.blacklist=nouveau"))

It seems that neither acpi_call nor bbswitch are packaged with Guix.
Is there any other commended way?

--
Pierre Neidhardt