The hurdles are too great for you to retreat from Ventura to Mojave, the last operating system to support the 32-bit iWork '09 suite. The defacto math syntax is now either LaTeX or MathML.
First of all, Mojave was only shipped on Late-2018, or the single TrueTone 2019 MacBook Airs. You would need an older Mac capable of installing Mojave 10.14.6, and nothing newer than the mentioned Air models would support a download of the Mojave installer.
Unless you have a MathType 6.7h installer laying around, the vendor (Design Science) was acquired by Wirris a few years back and any MathType support now is an annual $60 subscription with only Microsoft 365 (Windows) or Google Docs support. They have abandonded Mac, and may not offer the older MathType installer at any price.
The current Microsoft Word 16.72 uses UnicodeMath and LaTeX for entering equations, and when one uses the current Pages equation editor, it accepts a subset of LaTeX or MathML syntax and translates either into an embedded MathML object that survives the export to Word .docx and reopening in MS Word.
Apple documents what syntax is supported in the Pages/Numbers/Keynote equation editors in the article:
About LaTeX and MathML support in Pages, Numbers, Keynote, and iBooks Author
You want to download that linked blahtex PDF on the first page of the above link as it shows what specific LateX syntax is supported in the Equation Editor.
And, if you need help with entering LaTeX equations in the Equation Editor, post in this community and I will help you as I have done for others.