Because the notes are in markdown, so are portable forever even if Obsidian went away.

Well, not to diss on giving to charity but two technical arguments against. One is, you are acting as an additional tax on the worker (the source of the surplus) and then redirecting that tax to charity. It’s fine but the elected government has democratically selected priorities that they can rarely fund so it is better to just give it to the treasury. And 2, just don’t collect this tax in the first place, allowing the worker to spend it on the local economy.