In the mobile app market, a financially-viable or organic (non-paid) long-term marketing plan is the hardest. First testers can be hired. First users can be paid for with Google Ads/Apple Search Ads, etc. Depending on the competition, sustained user-base growth can become a next-to-impossible problem to solve.
If you have an iPad, perhaps have a look at modern general-purpose database apps[1], for example the object-oriented easyAsPieDB[2]. Object-orientation allows an end-user to define relationships among the relevant pieces of data in a conceptual manner, for example by using Composition (e.g., a House is composed of Rooms) and Association (a known Product is associated with a particular Order), while relational databases such as Microsoft Access force an end-user to define relationships among the relevant pieces of data in a more technical, structural manner, for example with Tables including generic "Foreign Keys" to other Tables.
I think the only reason vibe coding/prompt engineering seems to be taking over programmers' jobs is the fact that it currently enjoys the status of the latest investment craze/fashion such as blockchain did a few years ago and the dot-com boom did even earlier. In a few years projects based on AI generated code spaghetti will start to quietly fail one after another due to accumulation of technical debt and the necessity for manual, costly codebase rewrites and the whole AI coding train will come crashing down just like all other unrealistic, "new economy" fads before it. Companies will get desperate to hire decent programmers back and things will be back to normal.
Vibe coding/prompt engineering automatically accumulate "technical debt" of spaghetti code and thus with time cause every larger project to fail. Sooner or later you will be asked to fix all that AI mess in your company codebase and when you respond that you are unable to do so without a major, manual rewrite, you will probably get fired. Stay at your job for as long as possible, but start searching for a new position ASAP in an organization that declares up front that they do not intend to use AI for their codebase as a matter of company policy. There are actually companies out there already that make that kind of choice, but it might take a year or two for you to find such a job in the current job market. If all else fails, switch to the Linux kernel/driver development specialty with C/Rust for companies like Canonical.
I don't get all this prevalent "AI will replace everyone!!" hysteria. AI might be indeed pretty good at writing small, self-contained pieces of code such as a simple app or an API usage sample (in reality, not creating, but rather quoting or combining others' code), but AI fails miserably and utterly at maintaining larger codebases, not to even mention large, commercial-grade code repos. All AI can produce en masse is pathetic spaghetti code with no real-world commercial value. It actually takes longer for a human programmer to un... screw what AI has written than to write it all from scratch in the first place.
No. Quite the opposite. AI-generated code is quite often literally a laughingstock to someone with a couple of decades of coding experience and an active interest in architectural software patterns, e.g., code reliability and elegance.
From my experience, the "common assumption" that your brain works best only when you are in your 20s or 30s is a complete and utter nonsense. You might get a bit more burned out with time or simply become less passionate about technology in itself or professional careers in general and instead care more about your real-world life, but if you keep your body in good physical condition and keep pushing your brain, you only become more efficient and faster at programming every year, due to your accumulated experience and improved intuition. (Consider the Linus Torvalds guy.) It is only the corporate environment that actually forces you to switch to managerial responsibilities.
It's not just management. Neuroplasticity, from what I understand, can indeed be affected by your lifestyle (as you implied). But there's also the changing demands on your time. Many people are single or casually dating in their 20s and 30s, and have evenings and weekends to spend learning new things or playing with side projects. Then family and kids roll around, aging parents to take care of, eventually your own health issues... the demands of midlife and beyond will compete for your time and attention and leave many people with fewer resources (time, energy, money) to spend on intellectual gratification.
People like Linus are the exception rather than the rule, I think. Stallman maybe even more so? Sometimes I envy them, and sometimes I wonder how happy and balanced the rest of their lives are (maybe they're perfectly happy? I have no idea).
[1] "Airplane!" (1980)