Hi ~plasmon, and welcome to the Midnight!
You can type your posts in Gemtext here, and it turns out that there is a way to post mathematical notation in this format. You just create a preformatted text section (surrounded by lines containing triple backticks as in Markdown), and then place ASCII-art rendered math formulas and plots inside it.
Here's an example:
pprint(Integral(sqrt((1+x)/(x**2+3)),x)+Sum(1/j**2,(j,1,n)))
plot(sin(x),(x,-2*pi,2*pi))