I generated a sitemap (https://ycrm.xyz/sitemap.txt) for Google to pickup these pages. After many submission attempts, Google finally registered the sitemap and associated pages last December.
Now, it's been almost 4 months and the pages are still stuck in "Crawled - currently not indexed" in the Google Search Console.
Has anyone else run into this issue with Google before? Any help/advice is appreciated!
Rolling out a big site in one big bang does not look organic, if I had one bit of systematic advice it is "your site should look like a blog".
You need lots of external links to (i) the top level of the site, (ii) individual landing pages, and (iii) points in between. Webmasters will argue with me about this but I'd be mostly indifferent as to whether or not these are "nofollow" links or not although you want both (organic links to a successful blog are a mixture of both.)
If the text is all scraped and there is nothing unique there you are d00med.
Ideally you should have rolled out your pages and your links gradually over the course of four months, if you'd done that you'd probably be in good shape.
There are many things objectionable about the following blog but I think it can give you a deep insight into what's involved with SEO that you can get anywhere else, even though has not been updated for 12 years and the people involved have mostly moved on to paid advertising
In particular the idea that you don't want to make just one site is still pure gold. It really helps to make other sites that support your main site and to grab as much "real estate" as you can. You want a Facebook and a Twitter and a presence on 50 off-brand social media sites, forums, etc. Picture the amount of inbound links you need to generate you need to do and multiply it by 20x. The people most successful with SEO in 2023 are still doing this: I think of a Thai Restaurant in my town that has about 50 landing pages on different sites that mean it doesn't just get the #1 spot but it gets 6 out of the top 10. He buys ads too.
Back in the day the best sneaky trick I knew for accelerating indexing is to put an RSS feed in my site, make a Feedburner feed, and then subscribe to the feed. I don't know if this works now, but back then the Google index and Feedburner were joined at the hip and being active on Feedburner would accelerate indexing dramatically. Think "look like a blog".