Does Google index #! (hash bang) URLs?

Hash bang URLs are most definitely deprecated. Wix (a popular web site builder) is probably one of the biggest facilitators of getting people stuck in them.

The problem comes into play when you can never give a 301 Redirect for a hash bang URL from your end. Meaning that once you dig into using those types of URLs, changing sites/urls to somewhere else will be essentially next to impossible to retain your link juice for SEO purposes.

I've used hash bang URLs, because years ago I started with Wix's website builder, but it cost me severely when I finally decided I had graduated from Wix's crutches. Investing the time in any other builder, or even Wordpress themes, will not only pay off in the long run, but you'll be happy you never had to learn about old deprecated link structuring like hash bangs.

However, despite the limitations of #! URLs, Google definitely indexes these URLs and your site can be ranked by Google.

Googlebot is no longer crawling the _escaped_fragment_ URLs that the deprecated AJAX crawling scheme wanted you to create. See Google will stop using the old AJAX crawling scheme in Q2 2018.

Google still may be able to index your hash bang URLs, but only if they work with Fetch as Google from Google Search Console. Instead of providing a static HTML version of the page to Googlebot, Googlebot is trying to load all the AJAX and render the page just like human visitors with standard web browsers. If Googlebot can't do so, you page won't get indexed. The only way to check now is with Fetch as Google.