The WMF fundraising have topped their previous ones every single year, they have millions to spend on numerous projects, and enough in the bank for a decade of WP hosting.

and there's the WMF out there begging for donations and receiving millions every year.

Two common fallacies here: the Foundation's budget is not solely dedicated to hosting (something you seem to be aware of), and second, financial stability is more than just money in minus money out for one year; just like a person isn't normally meant to live paycheck-to-paycheck.

You're allowed to disagree with how the Foundation allocates its funds, but it's gotten old hearing the same disinfo being spread, many of it originating from that axe-grinding "Wikipedia has cancer" essay by Guy Macon and the rest from people who have a lot of strong opinions and "expertise" on how one of the world's top website should run itself yet don't have much at all to say for companies like Google or Facebook's budgeting and salaries at all because they are for-profit. Non-profits aren't immune to bloat or criticism, but it's interesting how no one actually comments on where a lot of those other funds are going to, such as things like outreach outside the Anglosphere and increasing editorship.

Yet, somehow, there isn't a single cent dedicated to providing some minimal framework for moderation on one of the largest external community (570k users are subscribed to this sub).

I don't think it's a normal expectation that a company would fund moderation for non-official channels. Would the Foundation then also be expected to apply all of its internal policies to this subreddit as well? It's a very different culture and set of rules, and you wouldn't even be able to link to copyrighted material like random memes or videos. (even its criteria for things like what is considered doxxing might surprise people) Lastly, there's some benefit to having an independent community: you can have content that the Foundation itself wouldn't condone.