I lead the DeepMind mechanistic interpretability team
What do you mean by giving to Manifund's regranting program? It's not one place to donate to. It's a bunch of different people who get regranting budgets. You can give to one of those people, but how the money gets used depends a ton on who, which seems important
If you're looking for something x risk related then I think something like the Longview emerging challenges fund is better https://www.longview.org/fund/emerging-challenges-fund/
I was surprised to see that you are US tax deductible (via every) but not UK tax deductible, given that you are a uk-based charity. I assume this is downstream of different levels of non-profit bureaucracy in the different countries? I would recommend explicitly flagging this early in the post as this is a deal breaking factor for many medium sized donors and if this was a constraint for me, I would have filtered exactly incorrectly
Google's donation match is $10k per person, and I would guess a bunch of donations from Googlers are unmatched