This is a brief response, so please don't rush intemperately into things before understanding what you're doing on the basis of any of this. For general finance information, especially about low-fee index investing, I recommend Bogleheads (the wiki and the forum):
For altruistic investment, the biggest differentiating factors are 1) maximizing tax benefits of donation; 2) greater willingness to take risks than with personal retirement, suggesting some leverage.
Some tax benefits worth noting in the US:
1) If you purchase multiple securities you can donate those which increase, avoiding capital gains tax, and sell those that decline (tax-loss harvesting), allowing you to cancel out other capital gains tax and deduct up to $3000/yr of ordinary income.
2) You can get a deduction for donating to charity (this is independent of and combines with avoiding capital gains on donations of appreciated securities). But this is only if you itemize deductions (so giving up the standard deduction), and thus is best to do only once in a few years, concentrating your donations to make itemizing worthwhile. There is a cap of 60% of income (100% this year because of the CARES act) for deductible cash contributions, 30% for donations of appreciated securities (although there can be carryover).
3) You can donate initially to a donor advised fund to collect the tax deduction early and have investments grow inside tax-free, saving you from taxes on dividends, interest and any sales of securities that you aren't transferring directly to a charity. However, DAFs charge fees that take back some of these gains, and have restrictions on available investment options (specifically most DAFs won't permit leverage).
Re leverage, this increases the likelihood of the investment going very high or very low, with the optimal level depending on a number of factors . Here are some discussions of the considerations:
My own preference would be to make a leveraged investment that can't go to a negative value so you don't need to monitor it constantly, e.g. a leveraged index ETF (e.g. UPRO, TQQQ, or SOXL), or a few. If it collapses you can liquidate and tax-loss harvest. If it appreciates substantially then donate the appreciated ETF in chunks to maximize your tax deduction (e.g. bunching it up when your marginal tax rate will be high to give up to the 30% maximum deduction limits).