This is an idea that fits very well for those newlyweds who already live together or, for any other reason, already have a home furnished and equipped and exempt wedding gifts.
The suggestion is to clarify already in the invitation that the grooms suggest that the presents are given in the form of donation. This donation can be in the form of money, which will be applied in some social project (it is legal to announce what the project is) or in the form of products that will be donated. Eg: Basic basket, toys, diapers, used clothes, etc.
It is nice, after the wedding, to publish photos of the delivery of the money or products to the favored entity. Not that this is obligatory, but it makes clear to all the guests that the donations have arrived at the deserved destiny.
For those who choose to receive donations in cash, the wish list of Soon Married is a good form of collection to be quite simple and practical.