There are several NGO-funded ships currently operating in the central Mediterranean Sea with the specific intent of saving migrants from what has been for years one of the deadliest migration routes in the world. Here is partial list:
Geo Barents (Médecins Sans Frontières)
Ocean Viking (SOS Méditerranée)
Aurora, Sea Watch 3 and Sea Watch 5 (Sea Watch)
Life Support (Emergency)
Open Arms and other ships (Open Arms)
Another important resource for migrants in distress at sea is the hotline AlarmPhone.
Since 2016 these rescue missions have become more and more onerous to fund as EU countries have progressively strengthened the Frontex program while at the same time criminalizing NGO-led search and rescue operations. (Italy has been at the forefront of this trend, and a shipwreck on the coast of Calabria in late February this year only managed to strengthen the resolve of the current government to make it even more complex for NGOs to try and rescue migrants.) So while it definitely won’t solve the root issue, donating to these NGOs still has a tangible effect.
I totally understand if you have doubts regarding these orgs but I can at least say that these are all ships that have been bringing people to safety in the last month. Big orgs like MSF and Emergency have been around for a long time, but on the downside search and rescue missions in the Mediterranean are only a small part of their operations around the world. More focused orgs like SOS Méditerranée and Sea Watch seem pretty dedicated to transparency in what they do, and while the Open Arms website is pretty sparse (or at least the English version is—Open Arms is a Spanish org) they definitely have been working in the Mediterranean Sea for years. In any case I left links so you can decide for yourself what seems the best option for a donation, and if anyone has additions to make they’re very welcome as well.
AlarmPhone’s service is active in the English Channel as well afaik, and has info for migrants trying to cross the sea there too.