I think I've hit a dead end for now, but here's a summary of what I've found so far:
-Most of the listings found by Google Lens are from Turkey, under the name “Hayalet Avcıları" (Turkish for “Ghost Busters/Hunters")
-The figures came in bags, not on cards
-They are approximately 10cm tall with no articulation
-In addition to the guys, the line also appears to include Stay Puft and Slimer
-The figures are all stamped as being part of “LOT-0482-L01," made in China, circa 2019, and appear to be officially licensed
-The stamps themselves are uniform, identifying the figures with their initials as follows:
--Peter: IT-0482-PV
--Ray: IT-0482-RS
--Egon: IT-0482-ES
--Winston: IT-0482-WZ
--Stay Puft: IT-0482-SP
--Slimer: IT-0482-SL
As I mentioned, the most success I've had in finding this stuff is searching images with Google Lens. Every now and then, new results come up due to new listings from these auction-type sites. For those interested, I'd recommend doing the same on a regular basis.