I recently got a 1" (25.4 mm) travel digital dial indicator that reads out in mm or inches. It has one little door holding a button battery, and it seems to have an un-advertised feature hiding behind door #2, which looks like 4 PCB edge contacts, likely for a data transfer cable. I assume this is something that someone uses in some factory tooling somewhere. Possibly logic-level RS232 data, but the company isn't interested in supporting it for all customers so they don't sell the cable for it. Anyone hacked into this? The brand is "Qnkaa".
I got it as Amazon item# B0CC5JVM3V Electronic Digital Dial Indicator with Magnetic Base Holder Fine Adjustable Long Arm 0-1" / 25.4mm Inch/Metric Conversion Professional Gauge 0.01mm/0.001"