When someone wants to die as a martyr for God it doesn't go as they expected. His calling is not so predictable.
How so? There's only one other option, which would be that they don't actually die. I can see how that might not be expected, but then that's beside the point.
Unless you're just giving money, there is no way to remain anonymous,
False. There are plenty of ways to help others anonymously. Dropping off food can be done anonymously. One can employ someone simply to allow the person the dignity of working for their daily bread without the other person ever knowing that their employer doesn't even need the work done in the first place. Perhaps someone needs a home for their family. You could ask them if they would be willing to house sit your home while you're away. This way you're asking them a favor without them ever knowing that you don't need a house sitter. The ways to engage in charity are only limited by one's own self interest. For everyone else, there is no limit.
charity isn't just throwing money at people.
I never suggested it was.
Someone has to labor for the good of others in the open.
Not necessarily, and when one endeavors to help others anonymously, the means of accomplishing that will eventually become quite evident. How many times have we all pretended that the poor soul in front of us dropped a fifty? C,mon, this isn't rocket science. It's really that easy. When they balk and say that they didn't drop it, you simply say that you clearly saw it drop to the ground just now, and you're not going to take it because it isn't yours. Most people will simply comply out of a sense of civility. The fact that they may desperately need the money is also a factor.
When your neighbor needs to purchase school clothes and supplies for their children, you can buy a chord of wood from them, or whatever else they have to offer, and then simply have it delivered to someone who needs it by telling them that you have a chord of wood you need to get rid of and perhaps they might be able to use it. The more you do this, the easier it gets.
I recently discovered that one of my neighbors has no electricity, and therefore no running water either. She's collecting rain water to wash clothes, and bathe. I told her that I had a couple of 300 gallon storage tanks that were lightweight, and needed to get rid of them, and that I could probably rig them up to her house in case the power went out during a storm so she would have water to flush her toilets. She graciously agreed to my request to take them off my hands.
Another neighbor was lamenting how their computer broke down, and they can't afford to fix it. I had a desk top that was just taking up space in my closet so I asked if they'd be interested in a desk top. Now they have done me the great favor of freeing up space in my closet. When people think they're doing you a favor, they will never know what's really going on.
So long as it is clear they are working as a Christian with nothing to gain for it in this world, their work glorifies God.
They don't have to identify as a Christian to glorify God. A true follower isn't seen by some pointless label, but by their fruit, and no one else needs to see it. There are plenty of people who gain nothing materially, but gain much in a better self image. In other words, they do it just because it makes them feel good.