If anyone from Germany is wondering, just found out that it's not possible to donate a kidney "altruistically" in Germany. You have to be a direct relative or a spouse.
Warum muss immer alles übersetzt werden? Nehmt doch einfach Longtermism
Some quick reactions to your points:
Please someone change:
That's why I would suggest something like GiveDirectly or AMF, those seem uncontroversial (but probably a lot more effective than planting trees)