Congrats on taking a 10% pledge! That's no small commitment and it's certainly an example for many to follow :)
I actually disagree with some of the previous comments around "Give What Feels Right" and that giving 10% is an arbitrary amount. What you've done in taking the pledge is you've created a baseline for your giving. You've made it a mandatory part of your spending, and are planning to do this for the long run. This baseline will keep you committed to the habit of giving, and it also takes away a lot of the internal guilt that comes with giving (e.g. am I doing enough?). You have a practice and you're sticking with it. Yay!
You're question tho is -- can I do more?
If you are approaching your FI number, I would begin to explore the following:
(1) What a wealth pledge looks like (vs. an income pledge). This will allow you to think more clearly about how to draw down on your portfolio. For example, if you took at 1% wealth pledge, what does your 30 year portfolio outlook look like? What if you took a 2% wealth pledge? In this way you are really thinking about your donations relative to your portfolio vs. your income. Which enables you to think more about drawing down. It's ok if this strategy changes over time, especially as you get older and you find more and more security in your financial plan.
(2) Explore the work of Aubrey Williams and Risk-Based Guardrails
. In a nutshell, he argues that you should adjust your spending based on how the market is doing. So for example, if the market is up X% percent, can you increase your donations Y% in that year? I think this is another clear way to use "the math" to flex your ability to give more.