According to the standard, it seems that basic MathML support is required for all conformant implementations (https://www.w3.org/publishing/epub32/epub-contentd

According to the standard, it seems that basic MathML support is required for all conformant implementations (https://www.w3.org/publishing/epub32/epub-contentdocs.html#sec-xhtml-mathml-rs-conf https://www.w3.org/publishing/epub32/epub-contentdocs.html#s...), but scripting support is optional (https://www.w3.org/publishing/epub32/epub-contentdocs.html#sec-scripted-content-rs-reqs https://www.w3.org/publishing/epub32/epub-contentdocs.html#s...). Not that anyone actually follows the standard…