So I have now made a little check-in app. It asks you to register your e-mail and a contact e-mail. Once you’ve done that, you need to login or use the quick check-in link once per day. If you don’t (maybe coronavirus has got you, or you’re not well), then it automatically sends a mail to the contact address you specified.
You can try it out here.
N.B Some web browsers will complain about “invalid security certificate”. I like encrypting and keeping your passwords safe, but can’t be arsed to register the website certificate just for a demo, so if you want you proceed, click “Advanced” or “Details”, and then “Proceed to website”.