I'm not sure what you mean by not having it, maybe you mean something different than what I'd usually mean -- on platforms I use it (Android), Google Sheets definitely has pinch to zoom (and it's been awhile since I've used Excel but I was pretty sure it did too -- the docs confirm it indeed does: https://support.microsoft.com/en-us/office/excel-for-android...).

Same for the Google Sheets app on iOS.

have you tried pinching on quadratic? it's smooth as butter/Figma, not at all like on gsheets

I have not but I honestly don't find it to bother me on gsheets whatsoever (I've never thought twice about it until now. Data entry is way way more annoying on gsheets than navigating is).