Sounds like a browser issue, not an Itch issue. In Firefox, if you go to Settings > Accessibility and click on Advanced Settings, you can disable all custom fonts for all websites. I assume that other browsers have similar settings. On the same Settings > Accessibility page there’s also an option to turn off custom colors for websites. If those are too coarse for you, there are also more nuanced extensions that allow you to change just specific fonts on specific sites.
Viewing post in Please provide an option to disable pixel font
Look, there are millions of websites and just a few browsers. While it would be great if those millions would all cater to all possible disabilities, this is realistically not going to happen. Meanwhile, the web browsers already have the features you are looking for, you just need to use them.
You complain about having difficulties with the pixel font, but that’s just one disability to cater for. What about people who can’t read the default font either, but need a dyslexic-friendly font? What about people who need large text? What about people who can’t read at all and need audio? What about people who don’t understand the language of the website? It’s not realistic for a simple game page to handle all of these cases, but it is realistic for a web browser to handle most or all of them, and most web browsers do.
Besides, the ultimate responsibility for creating a legible page lies with the people creating those pages, not with Itch. Itch is just providing the tools.
Which is not to say that Itch couldn’t or shouldn’t do more for accessibility. There are all kinds of features that Itch could and should provide, but don’t.