This is the bread-and-butter of what Linux distributions do. A large number of larger software are slightly altered in order to integrate this or fix that, but

This is the bread-and-butter of what Linux distributions do. A large number of larger software are slightly altered in order to integrate this or fix that, but they are close enough to the original that there's little confusion in practice that e.g. Debian's Mesa is still Mesa, and Debian's kernel is still Linux, despite alterations.