Google used to say don't be evil, and now one way to be less evil is to avoid using Google. For example, there's a market in privacy-friendly alternatives to Google Analytics, thanks in part to the all those cookie-warning popups mandated by regulation such as GDPR and the California Consumer Privacy Act.

I tried three of these analytics providers listed in the Ghost integration catalog: Matomo, Fathom, and Momently.

If your priority is a privacy guarantee, I'd say Matomo has the strongest one, stating explicitly that you don't need to add any privacy warnings if you use their product. Also, it's nice they don't require a credit card for their trial period.

However, I've settled on Momently, because they have a free plan and I'm cheap. The stats don't have a lot of detail beyond views/visitors per page, and the price of free is that the stats reset every 30 days, but that's good enough for me.