That's going to be very complicated, particularly with android devices, as not all devices can - or do - support the latest versions. And when you add in that legal restrictions prevent some makes from updating (cf Huawei / Google) and some countries from any access at all from time to time and you have a minefield of a project.
To add to that, there is no "one web page" this accurately lists any of this information other than Wiki:
Android version history - Wikipedia[
^] and that being user maintained is liable to delay and inaccuracy and the problem doesn't get any better.
A site scrape of
iOS version by device — iOS Ref[
^] might help with the iOS side, but even then you are at the mercy of unknown parties and their site design changes...
Good luck - I think you are going to need it!
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