I've been playing a lot since the Prowler became a care package weapon but I have rarely seen it or heard it in matches. Is it still a possible drop in care packages?
Taking an excerpt from the Apex Legends wiki page for the Prowler;
"As a care package weapon, it can only be found in Care Packages..."
So to answer your immediate question, yes it still exists as a possible drop from care packages.
Now for the part you didnt ask for! Reading up on how Care Packages function, there are essentially different "slots" items can spawn in, and each slot has a pool of items it chooses from. The "Center" slot has a 25% chance in Round 1 to spawn a weapon and a 75% chance to choose from the "Jackpot" items. In rounds 2 and 3, this number flips. Now looking at the spawn percents for the weapons themselves, the Prowler has the highest chance to spawn over the other weapons in round 2, however round 3 would also be a good time to go looking for one as well as that is the second most likely time it would spawn. So if you want to hunt for one, I would recommend you go searching during the 2nd and 3rd round of care packages. Note that my recommendation comes from pure speculation on the percentages on the wiki. Since this is RNG we are talking about YMMV.