make my laptop tell me when battery is low even while "show battery status in menu bar" is not checked

I had the same issue when I use a Bitbar plugin on OSX and have the default battery menubar unchecked. Here is what I use in my shell script to include a osascript call to create a notification pop up.

# Get info
power_source=( $(pmset -g batt | awk 'FNR == 1 {print $4$NF}' ) )
battery_level=( $(pmset -g batt | awk -F"\t" 'FNR == 2 {print $2}' | grep -o '[0-9]\+' ) )

# Notification when battery level is low
if [ "$power_source" != "'ACPower'" ] && [ "$battery_level" -le 5 ]; then osascript -e 'display notification "️⚠️ LOW POWER! ⚡" with title "Battery"';
fi

You could use this as a cron job. =)

There areo several free apps on the app store that will display your battery info and send notifications for certain levels of you battery. You should probably check there first and search on battery. Some options are "Battery Health 2" and "Battery Monitor"

There is a paid app named "Battery Charging Alert" which will do what you want. It will send you notifications when battery level is under some preset value. It puts a small window on your desktop with battery level info. The app is $5 from the App Store.