Excuse me if I am out of the loop and this is already available, but I haven't seen it and googling is not exactly easy as numpy introduces considerable noise.
With the introduction of the statistics module, the standard library provides basic statistical functions that can be useful in many scenarios, including teaching. The math module has plenty of mathematical functions that are very interesting, but no Matrix object. When newcomers want to have a matrix object, they end up implementing a list of lists (as suggested by the documentation, e.g. see https://docs.python.org/3/tutorial/datastructures.html?highlight=matrix#nest... and https://docs.python.org/3/faq/programming.html?highlight=matrix#how-do-i-cre...) but it's ambiguous (is each entry a row or a column?), and does not enforce types or equal length of each entry.
Generally, when a Matrix object is needed, numpy is the point of reference, but numpy requires understanding pip, installing modules, maybe creating a virtual environment and finally understanding numpy.
I would propose a simple, straightforward, low performance object to perform trivial operations such as matrix multiplication, transposition, addition, linear problem solving, determinant. The absolute bare minimum for an introductory linear algebra course. The syntax should mimic numpy to train newcomers to the numpy syntax whenever possible, and of course should implement the @ operator.
There is already a similar entity in the "array" module, which is a simple version of a numpy array, except that is only one-dimensional.