I, for one, am, a fan, of, Shatner commas.

They say insanity runs in the family. But it more like takes a stroll and takes its time to really get to know each one individually.

My pronouns are aahel/aahelim.

The unix philosophy is about making highly reusable and pluggable tools which is the exact opposite of what OP is asking for.

An example would be a REST API with a few endpoints where the database operations are handled directly in the route handlers uniquely for that specific task.

That's a prime example for untestable code (not testable with unit tests/without IO). That might be fine for a tiny experiment, but I'd advise against it for projects of any size, even private ones. Always use a model like MVC, MVVM, three layers (data, business, user) ...

I feel like we should have an in depth talk to better understand the problems you're facing and the line of thinking that motivates your initial request. Unfortunately I currently do not have the time for that. The best I can do now, with the best of intentions, is to advise you to read literature about software development. The trouble is, that I'm not sure what to suggest, because I think there's nothing that fits your premise. Maybe read about library development/reusable code so you better understand what not to make reusable by comparison? So maybe "Reusable Software: The Base Object-oriented Component Libraries" by Bertrand Myer or "Analysis Patterns: Reusable Object Models" by Martin Fowler. Though, both books are more on the old-fashioned side and I wouldn't recommend them if you're not an avid reader and (former) student of computer science.

Before I jump to "that's a really bad idea" with my 20+ years of experience: why?

I mean, sure, don't implement functionality you don't need, but making code not reusable intentionally? Why?

There was a building site next to our office and I stood at the window and watched the workers. A colleague walked up next to me. We stood there in silence for a while.

Me: "Sometimes I wonder if I should just fuck it all and become a gardener."

Him: "Me too."

Me: "I'm serious."

Him: "Me too."

We briefly looked at each other with expressionless faces. In silence we watched some more. Then we went to the next meeting.

True story™.

I actually had more success getting old windows games to run in modern linux with wine than in modern windows.

Story time:

My ex lived in another town and I went there by train. She waited for me on the station platform. I saw her first and took a detour over the neighboring platform because it was pretty crowded. I walked up beside her without her noticing me. Mind you, what follows was completely impromptu (we were both weirdos):

I looked sideways on her tits (she had nice really big tits, like, top 5% big). I spoke pretty loud so a lot of bystanders could hear it.

Me: Hmm, nice tits! Wanna fuck?

She checked me out from top to bottom.

Her: Sure, why not.

Me: OK. But, I gotta know what you taste like first.

Her: OK.

We went on to make the sloppiest wet kiss tongue-in-throat-style.

Me: Your place?

Her: Yah, let's fuck.

People looked at us in disgust, shock, or disbelief. Only one guy had the widest grin on his face. While going I gave her ass a good squeeze. The looks on the faces were priceless.