It’s possible that those 3 fingers may be collected or retrieved, but they were inside Yuji’s Domain so most likely they were 1) retrieved, 2) destroyed due to their charred appearance Megumi did say Sukuna’s 19F are gone, so we might have to take his word for it now

I thought Megumi said there was only 1 finger left on the outside, because Sukuna had 19 fingers. Megumi might not have realized that he spat out 3 of them. I think only the part of Sukuna that was in Megumi's flesh was torn off, but the 3 fingers weren't there.