I wrote a super simple python3 package called real2tex.

You can install it with pip:

pip install real2tex

And use it as follows:

from real2tex import real2tex

tex = real2tex(1.2345e-6, precision=2)
print(tex) # "1.23 \cdot 10^{\minus 6}"

If you want to see how it works or edit the code, you can found the source on GitHub. The code consist of only one file (/src/real2tex.py) and two functions.