Issues While Switching R to UTF-8 and UCRT on Windows

From version 4.2.0 released in April 2022, R on Windows uses UTF-8 as the native encoding via UCRT as the new C Windows runtime. The transition for R and its packages has been a non-trivial effort which took several years. This post gives a summary some technical obstacles found on the way, focusing on aspects that may be interesting to other projects.