I have lots of notifications in my setup (water the plants, empty the dryer, empty the washing machine etc). They all fire when the even happens, but actually that’s pretty useless when I am away.
I am now trying to find the best way to have those notifications to happen when I come home (something like if I come home have the Google Home speaker notify me that I should do this and that).
Has anyone tried something similar? And what would be the best approach to this?
FirstYou need some device_tracker-phone maybe to track you. Then add trigger and condition to automation, when device_tracker is home, trigger notifications this and that.
First you need some person / device_tracker-phone maybe to track you. Then add trigger and condition to automation, when person / device_tracker is home, trigger notifications this and that.
That’s the part I understand 
the problem is I need some kind of memory that stores the info on the triggers that have happened while I was away…
Notes:
Not truly persistent. Will be cleared on a restart.
The notification icon is now in a poor place if you have the side panel hidden and there is no way to move it back to the top view bar WHERE IT BELONGS 
An alternative could be to use the file notifications integration. Displaying the file contents in lovelace is easy enough. Have an acknowledge button that calls this custom integration (the file will be recreated when a notification is next made). You may also have to recreate an empty file (using the file notification) so the front end does not complain about a missing file. In this case call a script from the acknowledge button that does both things.
Do you know some python? I have a an app in AppDaemon that puts notifications on a what I call “briefing list” if the target person is not at home or sleeping and it is not an emergency notification. Once the target person arrives home or wakes up, all elements on the briefing list get sent to them.
I like @tom_l 's idea with the persistent notifications.
You can get a list of all with a template
To restore them on restarts, you can use this
Neat. I did not know that existed.
Is this app on your GitHub?
Yes it is see here. My documentation for this is, well, let’s just say lacking 
I can explain it in detail how it works and how you are supposed to use it in case you are interested. Let me know through a PM.