Not commenting on Google, but the problem with monopolies is you don't know what other and potentially better products might exist now if there was fair competition. Companies aren't going to fund a competing product when they know they're against a powerful monopoly.

"But the company being accused of having a monopoly has the best product and I like it" was said about Windows too when they were locking out competition. It's short-sighted.

Amazon, Ebay, Shopify pages, etc.

It doesn't really matter because google shopping is (or was?) just search ads with pictures. Every item shown was set up and paid for in Ads IIRC.

idealo.de tweakers.net/pricewatch .. in my corner of this earth.

There were / are plenty. Google's idea of being the only game in town is mostly marketing for almost all of their products.

From the top of my head: Ceneo, Cenowarka, Idealo, Skąpiec.

kieskeurig.nl/be, beslist.nl, kelkoo; all of which are relatively popular in just the Netherlands. Those are the few that survived by focusing on tiny niches; in this case a tiny geographic and language-demography.

Well, there are all those suggested by Google – oh, wait.

https://market.yandex.ru (only in Russian). Exists for over 10 years. Was my to go place to shop for electronics due to extensive filtering. It actually still is even after moving to US: I just pick the device there, then order on BestBuy/Amazon/NewEgg.

I used to use shopbot.ca but it became fully useless around 2 or 3 years ago.

Heureka and zbozi.cz are the big ones we use in Czech Reoublic.

kelkoo, prisjakt.nu, pricerunner.se

PriceRunner is big in Denmark.

heureka.cz

It's really nice to have thriving local internet.