I have such a hard time making onomatopoeias accessible.
The copies of the product have words like "omg", "mmmm", "wow" and I would like to make them accessible for all user using a screen reader, how can I achieve it?
Use standard HTML elements to provide the appropriate signaling to screen readers.
In your case, you can try using <abbr>
and <def>
tags.
These elements represent abbreviations and definitions within the web page. If you are using possibly unfamiliar terms, using these elements gives screen readers the best possible chance at assisting the user.
Additionally, be mindful when using them in conjunction with each other to achieve the desired result.