The Raspberry Pi Zero is still very hard to get – it seems to be constantly out of stock.
So I made Raspberry Pi powered* Raspberry Pi Zero Checker: It scans Adafruit, Pimoroni and The Pi Hut for strings indicating stock and warns you with an annoying ‚alarm‘ sound. I also have a PHP version for my web server that also works very well.
*Note: any computer will do – but a Pi can be left on all the time without annoying fan noise or high power bill.
This is a very simple project both soft- and hardwarewise: Get your Pi online, automatically start the script on boot (rc.local or systemd) and plug in some speakers.
If you do not want to get woken up in the middle of the night, you might want to add some code to not trigger the alarm after 22.00h for example.