If you want to do your own thing, you can simply download these Markdown files (see the link at the top?) and use them as a "starter pack" for your own set of connected notes that you change to suit your preferences. The notes should work well in various markdown editors, but the spaced repetition prompts are written in the format that works in the obsidian spaced repetition plugin. That said, it is pretty easy to mold the pages to your exact preferences at scale these days using agents and agent skills to manage your markdown notes!