The swap_fn_leftctrl module option invoked in /etc/modprobe.d/hid_apple.conf:

options hid_apple swap_opt_cmd=1 swap_fn_leftcrtl=1

is not working. The first module option, swap_opt_cmd does work. I also tried separating the options into separate lines. The above file does work in the Debian Bullseye system that Pop!_OS replaced. Checking dmesg shows:

[    2.000711] hid_apple: unknown parameter 'swap_fn_leftcrtl' ignored

On the other hand:

# echo "1" > /sys/module/hid_apple/parameters/swap_fn_leftctrl

does work.