Pretty lame with just model numbers, it would be nice to at least have a one-liner so you didn't have to link to each one to see what it is!
MTH actually publishes this list for each catalog on their website. I don't think they intend for regular web users to find this list perhaps it's used to generate SEO for web searches or used as a lookup source for the "product locator". I stumbled upon it while scraping the entire website for offline use. For example, here is the link to the same list for the 2020 V2 catalog: https://mthtrains.com/catalog/fi-2020-volume-2
None the less, it is a comprehensive list for all scales of everything being built for 2021. They do add to it as new thing have been announced.