In the UK, for any of our charities to invest, an investment fund would need to have a legal entity and governing instruments - Articles of Association, or similar, depending on which legal form they took (that's leaving aside Steem price volatility), and we would want a legal form that avoided tax, if that were possible, given the nature of the investment fund :)
I am thinking about going to talk to the two local credit unions, although it might be too early for them to become involved.