Bitbar (https://getbitbar.com) plugin. Copy to plugin folder and add X permission (`chmod u+x apple-mouse-keyboard-battery.1m.sh`)

apple-mouse-keyboard-battery.1m.sh

#!/bin/sh
# <bitbar.title>Apple Mouse and Keyboard Battery Percentage</bitbar.title>
# <bitbar.version>1.0</bitbar.version>

INFO=$(
    ioreg -r -l -n AppleHSBluetoothDevice |
    egrep '"BatteryPercent" = |^  \|   "Bluetooth Product Name" = ' |
    sed 's/  |   "Bluetooth Product Name" = "Magic Mouse 2"/🖱 /' |
    sed 's/  |   "Bluetooth Product Name" = "Magic Keyboard"/\⌨️ /'|
    sed 's/  |           "BatteryPercent" = //' |
    sed -E 's/([0-9]+)/\1% /'
);


if [ "$INFO" ]; then
    echo $INFO " | size=12"
fi