One of the things that matter when you create something is whether it will last. Meaning, if you make something today, will it still be usable tomorrow? What about a month or a year from now? What about 10 years from now or 100 years from now?
Some technologies just last longer than others. Some languages are less transient than others. Some storage methods and platforms last longer than others.
From that perspective for languages,
For storage mechanisms,
b2 > a cd > postgresql > some startup web app
Or something like that. I don't actually know a truly durable way to store data, especially private data. The closest thing to it that I know of is object storage (like s3 or b2). But there's always plan risk (the company may alter the deal around the service) and credit card risk (somehow payment may get disrupted and then the data is lost).
Actually, that seems like a fairly good idea for charity:
Provide durable, inalienable, private storage for every person. Say 1 Gb each, at least at first.
As a first guess for durable platforms,
Web > Desktop Operating Systems > Mobile Operating Systems
Within Desktop, probably
Linux > Windows > Mac.
But again, I don't know.
In the end the details of what lasts and what doesn't will matter very much. For this post, I've made guesses, so the details are unreliable. But the principle of thinking about what will last and what won't matters even if I didn't get the details completely correct.
You only have limited time to make things. Maybe it's worth thinking about how what you make can last.