I think a handbook for post apocalypse is a great idea. You may need to do several with different main topics. Subjects like law and farming could (and do) have so much information that they could be books of their own. Depending on the type of apocalyptic event you could also point readers towards other books on more in depth subjects.
How to Invent Everything: A Survival Guide for the Stranded Time Traveler https://www.amazon.com/How-Invent-Everything-Civilization-catastrophes/dp/0753552566/ref=tmm_hrd_swatch_0?_encoding=UTF8&qid=1659029440&sr=1-1
It has a lot of interesting things in it. Maybe it could give you some ideas.
Click this if it works, or just search seed on costco.com....
Cool. I thought you were asking for suggestions but you weren't. :)
I think the issue with what I linked or maybe yours is water-tightness... is yours? The one I linked, I don't think is that much...
If you have an Android/iOS device with GPS, consider the Tasker app.
Users can trigger actions based on the occurrence of events. For example, respond with your latitude/longitude when a loved-one texts with a certain keyword. Or regularly post the same details to a time-stamped google spreadsheet.