WML pages had mostly text and hyperlinks from what I remember and even though it supported images too I think most such basic pages would be readable even if you turned image loading off.
I spent so much time tuning the WAP site for the forum I worked for back in 2008.
I had some sort of Nokia running on whatever 2kbps networking was going then, and would shave absolutely anything I could to make the forums load slightly faster.
https://en.wikipedia.org/wiki/Wireless_Markup_Language
https://en.wikipedia.org/wiki/Wireless_Application_Protocol
WML pages had mostly text and hyperlinks from what I remember and even though it supported images too I think most such basic pages would be readable even if you turned image loading off.