And because it's a fork of 'mirror/newlib-cygwin', searching for "picolibc" on GitHub does not find it, even though this project has 678 stars and the original newlib-cygwin has only 144 stars. Why is GitHub search so broken?
Seriously though: Making your fork "unhooked" from its parent is not very difficult, it only takes one support request and they usually get back to you within the week.
Independently of that, yes, search should find forks too.
For me it was discoverable via the fourth and tenth results.
picolibc
1. 005 https://github.com/mtottenh/picolibc
2. 005 https://github.com/litex-hub/pythondata-software-picolibc
3. 005 https://github.com/AshlingMicrosystems/picolibc
4. 005 https://github.com/ft/zephyr-picolibc
5. 005 https://github.com/keith-packard/picolibc-ci
6. 005 https://github.com/modm-ext/picolibc-partial
7. 005 https://github.com/philpem/picolibc-docker-arm
8. 005 https://github.com/antmicro/pythondata-software-picolibc
9. 005 https://github.com/likewise/riscv-picolibc-docker
10. 005 https://github.com/picolibc/pico-hello
11. 005 https://github.com/libhal/gcc-arm-none-eabi-picolibc
12. 005 https://github.com/keith-packard/simple-mps
13. 005 https://github.com/picolibc/simple-mps
14. 005 https://github.com/swiftgeek/stm32f103-demo