Alas, no, I don’t know of a replacement for ngram! But personally I don’t mind ngram at all — my objection to using Google search is not really that it’s a google product (with all the problems of monopoly that accrue from Google’s monopolistic-ish position, and the bad downstream effects that flow from that, say) but that the UI design is, for me, totally wretched and a hassle. I’m lazy; if they made a better UI I’d probably go back to using them as my main!

Ngram, in contrast, is beautifully made — a nice, simple, single-purpose tool that’s clear about what it’s doing and how it’s doing it; which is, alas, what Google Search used to be