I found this note combination feature request but it doesn’t look like any plugin or native solution exists? From reading the thread, possibly you could make your document with all the transclusions then export as markdown which should then pull the transcluded content in. There’s also this short thread but it seemed focused on pulling entire notes in; not sure if that’s what you want or not.

Edit: and this is why I shouldn’t research things on my phone! Obsidian doesn’t have a native markdown exporter, just to PDF… there’s “Obsidian Enhancing Export” plugin, and “Obsidian Markdown Export” plugin. and a paid plugin.