That's a good point on the signer.

I believe what I've heard Graham and Nate from Voltage both say, and what is listed in one of their blogs Nate wrote, is that they are a "non-custodial, but not trustless" service.

Ultimately, we serve over 14,000 organizations worldwide with a native mobile app on Apple, Android, and in some cases tvOS and Roku. It'd be great to turn on a Lightning interface in our ~100 million apps currently installed on peoples' phones around the world. So they could not only donate Bitcoin to the orgs whose apps they've downloaded, but be interoperable with any other Bitcoin + Lightning wallets for p2p.

On the non-custodial side, it'd just be nice to do this in the spirit of Bitcoin's original ethos. But we would also have to balance the need for nonprofits to issue tax docs for deductions from the donations if their jurisdiction allows for that. As well as their need for liquidity.