Check the detected licenses in the scan of https://www.nongnu.org/avr-libc/ and https://github.com/picolibc/picolibc

[pombredanne]

https://www.nongnu.org/avr-libc/ and https://github.com/picolibc/picolibc (which reuses some of it and part of newlib) have a varied licensing which would be worth double checking.