You see my point is that I'm deep into retro-computing thing.
I would like to learn some new, fresh language instead C, C++, BASIC or PASCAL, but on my real old hardware - so I could test various stuff and FELL the "speed" of my 25Mhz CPU :)
But what is more fun than artifical retro is programming microcontrollers. A project that needs a hundred or a thousand microcontrollers puts an upper bound on their cost and complexity, and so real, practical limits on their individual absolute capacity. At the end you get something you built yourself that you probably couldn't buy at any price.
You can program microcontrollers in C++20, and use all the most powerful features of the language, which mostly happen at compile time on your host/development machine, downloading the resulting binary into your microcontrollers. You can debug on your host with gdb, talking bit-serial to a tiny gdb stub you have included in the code running on your microcontroller.
If you want to use a newer language, Rust or Zig are probably not much harder to get generating code for microcontrollers.