I remember arriving in Lisbon, leaving a favorable review for a restaurant because they were so nice to us, and Google sending me a notification that I'm now a local guide for Lisbon.

What exactly does that mean though? Is there any benefits to it? All I see is a badge/label, that's it?

I really don't know why anyone would try hard to get that. On Chinese map app (Amap) at least you can get a ride hailing coupon, for a nice taxi discount.

If you accrue a high score, Google should give you a plaque like they give to Youtubers with many subscribers.