I've been using Any.type for a bit over a year, and am very happy with it, but I don't believe it has hand writing support.
There is a free tier that includes 1gb synced storage (optional).
It's open source. Somewhat similar to Obsidian, but no plugin support that I'm aware of.
Music is a no brainer for me since it's something that is infinitely re-enjoyable (if that's a word) and it doesn't have to take up much space, without reasonable compromises to quality.
I bought a digital audio player last year so that I could be offline and disconnected when I go out but still enjoy music. One of my favourite purchases the last few years.