You know what I'd pay for? A charity that independently audits other charities.
It could regularly investigate other charities to ensure all their operations are legit, and then publish public reports on how much of their funds are actually being used for charitable work and how much are just being used on paperwork or administrative bonuses.
The only issue is that the charity auditor will attract malicious actors, and then you have to audit the charity auditor. Then you need to audit the auditor who audits charities. And so on...
And yeah, I hear ya @ILikeYaeMiko, there are just so darn many charities. I don't have time to research them all. I think it's probably best to volunteer at a local charity to see how they operate, then donate to them if you choose to support them further. Honestly though, volunteering is enough of a contribution - Labor is just so necessary for getting anything done.
(I wouldn't be surprised if something like the auditing charity exists already. Of course... One would have to research them too...)