My biggest problem with any gmaps alternative is the missing ratings option. So far I only found mapy. I am very happy with the app but wanted to check if there are any apps that might also be worth a look. Gooing in a restaurant without looking at ratings is a bit to adventurous for me.
https://mapcomplete.org/ has reviews in some maps (such as the food map); but there are not a lot of reviews as of now. So, go out and review ;)
They seem to use another service ( https://mangrove.reviews/ ) to save the reviews. On first read this does sound interesting and I will have a look at it. Thanks :)