Why not a pick a language of choice and write some ambitious framework/library? Like Numpy/Pandas for Python. Maybe a web development framework? That way, there is a reasonable chance your work will be noticed or used. Look Maybe pick Julia and write a library for it. I believe Julia doesn't have as many libraries as Python does.
By the way, as much as I know, all the languages were written by 'old' people. Young people rarely have that much knowledge or experience. They don't even know one language fully well. So age is actually at your side.
If it is to be used as a "reader" device then, well, whatever. But in that case why not just use a "reader device" then.
I'd rather work on my paranoia than on getting a fully secured device.
By the way, I am writing this on a mobile with 2 GB RAM and running Android 9 as my other mobile got broken.
It would have been better if they offered slightly longer security updates in exchange of only letting you change the battery. Other things probably won't break anyway before the security updates stop coming in.
I guess tech people are way too much worried about security/software updates.