obsidian-system-dark-mode VS obsidian-annotator

There’s a plugin for it: https://github.com/kepano/obsidian-system-dark-mode

That said: - I assume you will be doing at least some highlighting / annotating of pdfs and / or websites. In that case, you might want to look into either plugins that automatically import your highlights from other tools (Zotero, Kindle or another e-ink device, Hypothes.is, Readwise, etc), or into plugins that allow for highlighting PDFs directly inside Obsidian (Obsidian Annotator). - Templater is useful for most folks that have to create many notes with repeated layout. If you have notes for each lesson, you could have a lesson note template, to create them faster and keep them consistent. - As a student, you have to keep track of your schedule when it comes to classes, exams, etc. - you could use a plugin to sync your existing Google calendar, or keep your calendar entirely in Obsidian (Full Calendar).

You should check out this plugin, it greatly enhances pdf annotation from within obsidian https://github.com/elias-sundqvist/obsidian-annotator

What I really like about Logseq is their pdf annotation and highlighting feature. You can open the pdf in Logseq, highlight text, drag it into your document, then work with it. Upon clicking on a highlight, it opens the pdf at the page of the highlighted text. I found that the "Obsidian-Annotator" plugin in Obsidian can do the same.

I am aware of other plugins (such as obsidian-annotator) but since I'm already using MarkMind and I have PDF annotation capabilities, I thought it would be nice to conveniently use the features I already have without installing another plugin. Is this possible?

Have a look at https://github.com/elias-sundqvist/obsidian-annotator

Install the Annotator community plugin and follow the setup instructions.