that's backwards
You seem to think it is Google's job to make iOS easier to use. There are plenty of tablets out there which can run chrome/Firefox/opera/Vivaldi/palemoon and would happily run Edge or Safari if the authors of those browsers elected to publish them. I too have some family who .... struggle .... with things technical, but even they learn very quickly after you show them the "internet button". Of all the .... limitations .... in Safari, for me, the icon is way down on the list. In fact, I will admit to liking that icon. If they need to see the Chrome icon, any of those tablets will suffice.
The rendering engine isn't some abstract concept. It is the biggest difference between ie6 and modern Chrome. Poor* rendering engines directly hurt your experience. They may be slow, use more memory, draw incorrectly (or fail to draw), and fail to protect you from threats by ignoring CSP rules. It directly influences whether you think your tablet is too old which costs you real money if you buy a new one.
*and add to that poorly maintained