For some reason sitemap.xml protocols use http not https to have them in your XML sitemap. Also, sitemaps.org is wrong, search_engine/ping is now deprecated and does not work. You can submit via special portals but you will need to add a DNS record. I found for bing, Webmaster tools. That helps with a lot of things like DuckDuckGo and Ecosia. I also found for Google, Google Search console. Next I found Yandex webmaster tools. There is also Baidu in China but I hear it is in Chinese. You will need to add some permanent record to register with these. If you don't like adding things for search engines, tough. You will need an account with Google for submitting to Google. I found there is an index individual URL option with Google and Bing, I recommend using it for much faster website search show up.