Should I include tags and categories in the sitemap.xml of a blog site?

Question

Search Engine Optimization

Actually the question is in the subject, here https://wordpress.org/support/topic/sitemap-catego... they also post the use of parameters, frequency and priority of crawling, for each endpoint. But I wondered if including tags and categories in the map would lead to duplicate content. In general, now I'm leaning towards making a map only for:
- HomePage
- Posts
- StaticPages
And by the way, the most important question is, "Should I include sitemap.xml at all in 2020?". In Yandex, for example, when registering, the map is optional, while Google recommends including the map, and even with the Atom / rss feed, there will be a cake in general. On the other hand, this is not so critical for a blogger, probably, as for large publications, it is clear that this will not affect the ranking in the SERP, but only the indexing speed.
And here's another thing, I wanted to abandon sitemaps and feeds in favor of pinging, that is, I created / updated a post, sent it to
Services. I decided to test it, pulled out the pingback.ping request method to services from WordPress, this one ping.blogs.yandex.ru/RPC2/ is generally dead, and blogsearch.google.com/ping/RPC2/ - "Method is not allowed", In general, doubts about the expediency of this method immediately began to appear (I did not check pingomatic). In short, who thinks or does what.

Answer 1

a sitemap is needed
next, a competitor is taken, with traffic, and what is done with him is duplicated