Regarding “this account for your Mastodon posts”, I don’t use an “account”, nor any “Mastodon posts”. I have my website, https://tantek.com/, and use it to directly post notes & replies (like this one). Previously I had a https://xoxo.zone/ account which I have redirected to my website.
Regarding, “not using any other Mastodon accounts”, there is no need to use any other accounts, Mastodon or otherwise, when you can post all notes & replies on your own site where you fully control the display, design, markup etc., without depending on an instance admin.
#IndieWeb building blocks and Bridgy Fed (https://fed.brid.gy/) make all this possible, as described in my post: https://tantek.com/2022/301/t1/twittermigration-bridgyfed-mastodon-indieweb