>>3551570It's not exactly Sony-specific as it's the old Minolta remote connector that was introduced along with the A-mount back in 1985 and kept when Sony bought Konica Minolta's photo division in 2006 (it's still found on Sony's latest A-mount SLT, the α99 II).
RC-1000S or RC-1000L (Short or Long cable) are the Minolta references, RM-S1AM and RM-L1AM for Sony.
If you search those model numbers on Google/eBay/AliExpress you'll find lots of compatible remotes.