There are ways missing to donate directly by giro account to giro
account and to do an anonymous in-payment to a giro account.
Everybody of us, even the most poor of us, sometimes have little money
willing to donate it, but not all of us are willing to do it by the
options that are often provided instead of a giro account.
In Germany there are donation accounts for some things, so it's easy to
transfer or to pay in cash.
Perhaps you could statutorily regulated hold in trust such an account?
This IMO would fit better to the policy of FLOSS than advertising does.
Advertising will lead to hype with all it's consequences.