The Arduino 1kHz busy-loop and ISR designs is not real-time or necessarily guaranteed latency.

RTLinux or FreeRTOS are guaranteed-latency OS, that can reduce timing jitter.

"Real-time" is another term hijacked by people that think it means the same thing. It was a disservice to students, but thankfully FPGA or Raspberry Pico io DMA with mcu parallelism can teach people to understand clock domain crossing.

Part of the Arduino appeal, was convincing people the mcu and application SoC problem domains were the same. They are not, and never were... Hence the new Arduino board dual chip layout is twice as bad in some ways. Cheers =3

https://www.youtube.com/watch?v=G2y8Sx4B2Sk

risc v -- a new hope, but 20 years too late

stm32 -- a solid competitor to Microchip/AVR, but 14 years too late

esp32 -- FreeRTOS with hardware flash paging can pose an issue, but at least it already doesn't need Arduino software lol