I would strongly argue against Notion. Any app that requires me to watch 3 tutorial videos just to make it do anything isn’t worth it and there is a big question about ownership of data.

For a quality ‘everything’ note taking app OneNote can do all the same things and is free at the point of use. Your data is sat on your free-or-otherwise Onedrive account and is just as usable across Android, iOS, Windows, Mac and the web.

Apple Notes is a worthy successor to Evernote now that has fallen off a cliff in terms of its pricing structure. Its natural drawing extensions make it incredibly powerful and again it is completely free. The Android web version is lousy but it works very well on Windows and Chrome in a browser.

I would actually argue against Obsidian on Apple devices. Your data might be stored in a local or iCloud folder but you cannot get at it outside the Apple ecosystem. Using OneSync as a backbone you can easily sync a local Android folder back to OneDrive (and therefore a PC) and use Obsidian cross-platform without forking out for their subscription.

If you’re really looking to save money then regardless of platform you can produce better looking assignments with Apple’s iWork apps on iCloud.com than anything from Microsoft or Google and you can do it all for free.