I've implemented Google Custom Search Engine on a few sites before, and it's not clear if this is the same (repackaged?) or different. The biggest question (as with many Google products) is when this it going to be shut down, given that Google Search Appliance itself reached its end of life in 2019.

If you want a dead simple way to integrate search onto your site/app but find the learning curve of something like Elasticsearch steep, take a look at this project that I've been working on:

https://github.com/typesense/typesense

Typesense is an attempt to offer a great search experience out of the box -- with minimal configuration. It also supports clustering/HA, so you can certainly go a long way before considering something like ES (which is a great product but also pretty beefy).