You should create an XML sitemap and dynamically add new dynamic URLs to it. There is now need to use
lastmod in an XML sitemap. Google says they ignore
lastmod because few sites keep it up to date. Googlebot will notice any new URLs in the XML sitemap and will come crawl them whether on to they have a
You should not create a single page that links to all your dynamic URLs. HTML sitemaps don’t work well for SEO anymore. XML sitemaps work fine for getting your content crawled.
When you have an XML sitemap Googlebot will come crawl all your content. However, it is likely that most of the URLs in it won’t get indexed. If any of them do get indexed, they won’t rank well. This is called The Sitemap Paradox. To get most of your dynamic URLs indexed and ranking, they need to link to each other. That is why this site has the “Related Questions” section on each question page.
Your home page should link to a few of your best and most recent URLs. Those URLs will in turn pass some of that link juice on to other dynamic URLs.
Once some of your URLs get external links, the link juice from external links will be passed further to other dynamic URLs as well.