That's one thing I can't seem to quite figure out with those solutions. I know there are scripts out there (or I could try my own), but that seems error-prone and could result in failed backups.
restic [...] && curl <heartbeat-url>
Restic is also confusing to me with forgetting snapshots and doing cleanup, I don't understand why that isn't run as part of the backup (or is it? The docs aren't clear).
You don't always want to forget/prune snapshots. Especially if you're using a cloud service like B2. It can easily cost you more to prune than actual storage costs if you're not careful.
See here: https://www.seanh.cc/2022/04/03/restic/#maintaining-your-bac...
and
https://kdecherf.com/blog/2018/12/28/restic-and-backblaze-b2...
On Linux I used cron + email. You can setup postfix such that you use your personal gmail or whatever, then you will be able to do "echo message" | mail -s youremail.com to send an email. They (big email providers) always allow you to send an email as yourself to yourself.
On Windows, I used the native task scheduler (with various triggers like time, lock workstation, idle and so on) and send an email using powershell, which can also send emails using SMTP.
I expect an email every day. If I don't receive one, I know there's a problem with email delivery.