UNRWA: https://www.unrwa.org/

Doctors without Borders: https://www.msf.org/

Both should be safe from landing you on a list. But tbh, who knows nowadays?

The problem is not so much that donations are missing, but that Israel blocks the aid. Despite that, donating is still important.

Doctors without Borders would also know, if nurses are needed, and more importantly, if nurses can get into Gaza. You should know that health care workers (including Doctors without Borders personell) has constanly been directly targeted by the Israeli airforce and you would, without a doubt, be in life threatening danger. More than 880 health care workers have been killed by now (https://www.doctorswithoutborders.org/latest/our-response-israel-gaza-war).