If there is one service I find immensely valuable, push notifications is it. I've been relying on Pushover for years now, and I have to admit it has never let me down.
Discovering Gotify made me all warm and fuzzy inside 'cause this was the first time I knew that I didn't have to worry about the chance of Pushover going out of business.
I'm using a command line calendar called remind that relies heavily on push notifications for me to receive notices in time. Now everything is in place for this system to work till the end of days, or the end of Google for that matter ;)
It is one of the few servers that I'm actually thinking of exposing online since that would make it work no matter my network location. Running it behind a VPN as I do with most of my critical services needs the link to be always up, something that is not always guaranteed.
There is a whole slew of helping applications built around this amazing service like Linux desktop notifications, docker image updates, command line app that works in tandem with your local services to provide any info necessary. The use cases are endless with this one. There is of course a docker image available that makes the whole initial setup a breeze, so why wait, give it a spin now!