I am not sure what you have read about major companies being hacked, but a majority of the time they don’t even get to the users actual data. They might only get access to your name or other information. It is extremely rare for them to get access to to all of your data, especially if the proper security measures are taken.
As for the monetization, I will need to eventually charge something since making an app isn’t exactly free. I was thinking of making the core features of the app free, but then charge for premium features. I may allow you to save 200 items on your map, then you will have to buy premium for 4.99 a month (This is only a coffee a month).
en.wikipedia.org
It's not paranoia if it's true. The frequency of data breaches is irrelevant, as it only takes one time to have important data exposed. Once it's out there it's, at the least, a big hassle to undo and/or mitigate any damage. Not every breach is going to expose sensitive data, but
any exposure can give a foothold to the groups that make use of these data, and help them to find targets for future goals. Even if you think a certain datum is innocuous, if exposed, it can point a criminal in the direction of the data they desire. With the advent of AI, it's much easier to make use of small bits of data to correlate them to a single person. Yes, most of us won't
qualify as a potential target, but that doesn't mean we won't be used as a
test run. The way privacy has been going for the last couple of decades, most things that
would have been considered a data breach are now given away freely by the pubic
en masse. Anyone who uses a smartphone, on default settings, is
constantly giving out there GPS location and are, subsequently, targeted for advertising based on their proximity to certain businesses. With most devices now constantly
talking to each other, many times by default(you have to tell most devices to not to do it), very little of our lives are
not being recorded for future use.
With all that said, and in reference to your original question, you really have to ask how many of us, young or old, are that
hardcore about detecting that we would want to map out every single find, report them, overlay maps, and need a central repository for research, and whatever other features you decide to include. Me, personally, I avoid giving my
actual information whenever possible. Yes, I know I have to give my info to banks, government agencies when needed,etc., but on the internet, I often give false information. Your idea for an app is good, but, as others have pointed out, is there really a demand for it? When I do research for a site I do it at home, before I go detecting. I don't grid, and I, more or less, meander around a site, and enjoy being outdoors. I remember where I find most things, and I'm not trying to reconstruct the habitation of an area. I'll leave that to the archeologists. If you examine all the detectorists in this
niche hobby, I think you may find that very few of us are organized enough to want access to the features you're proposing. I could be wrong and I'm one of the few who doesn't grid, and map everything. I basically make use of the free resources available to me to get a
general idea of where to hunt. I definitely don't want to be doing it out in the field; I have enough stuff to carry as it is. For me it would be more of a distraction, and I'd be spending more time on my phone than actually detecting.
As I said, it's not a bad idea, but you may want to further examine if enough interest is there, and how many people would be willing to pay for it. Good luck in whatever you decide!