Hello there,
I am an experienced programmer. I can do C/C++/Rust/assembly/Ruby/Perl/Python/ etc.. The language itself is not a barrier.
The barrier to me is that I have never coded a single web or android application. I guess it must be surprising but I am more of a low-level programmer in my job (I develop a compiler backend) and I never really had the opportunity or idea to work on an app.
What would be a good starting point for making an android application?
A quick search got me this: https://google-developer-training.github.io/android-developer-fundamentals-course-concepts-v2/unit-1-get-started/lesson-1-build-your-first-app/1-1-c-your-first-android-app/1-1-c-your-first-android-app.html
Would it be a good starting point?
Side note: my app will not have to interact with any service. If I were to code it as a command-line program, it would not take me more than a day or two. The actual app would involve (for now) no more than a text field, a button, some logic attached to it - the hard part for me being to choose a framework to build it, "upload it" to my phone and use it.
Have you considered writing a responsive web app in JavaScript that can be hosted by GitHub Pages? Depending on what exactly you need to write and what you need the program to do, that may not be the best option, but it is simple, you don't need to worry about hosting the site, and it allows you to rapidly deploy your application and make it accessible anywhere through a web browser. You just write the HTML, CSS (if you wanna be f a n c y), and JS. No shortage of tutorials on those 3 languages.
Here's a few examples I've written:
https://github.com/mpm11011/hanafuda-react
https://mpm11011.github.io/spirit-island-tracker/
Vger.app is another one