I would rather use the non-atomic shared pointer from Boost[1] linked upthread than a non-standard non-portable implementation detail from GCC, but yes, it exists.

You can definitely implement a non-atomic non-threadsafe shared pointer in C++, my point in the article is that actually using it is very error prone. This is supported by the type being excluded from the standard library with one of the reasons being the risk of bugs.

[1]: https://www.boost.org/doc/libs/1_65_0/libs/smart_ptr/doc/htm...