Unless they are permanently only using specific addresses or blocks and will never change that up, I’d consider it a moving target.

A flatpak of the snap, running in a docker container inside a vm for maximum security.

Checking ip ownership is a moving target more likely to result in outcomes these sites don’t want (accidentally blocking google bots and preventing results from appearing on google).

Checking useragent is cheap, easier, unlikely to break (for this purpose, anyway) and the percentage of folks who know how to bypass this check is relatively slim, with a pretty small financial impact.