USB receiver for the IBM SK-8807 Infrared-only keyboard
github.com
github.com
With the hobbyist USB receiver, it enables a line-of-sight wireless keyboard that is not vulnerable to radio baseband and other attacks on Bluetooth and WiFi connections.
There was also an independent implementation of the IR protocol on an STM32 device, https://forum.vcfed.org/index.php?threads/ibm-ipoint-keyboar... & https://github.com/Tubatstuff/IBM-IR-PS2-stm32
There was also a really cool foldable keyboard for PalmPilot as far as I remember. Might be a good option for this treatment too. Probably even easier.
I remember at around the age of first OHA phones, Japanese all had IrDA ports, but google has persistently stonewalled IrDA inclusion into Android mainline.
Sharing things were super easy on my Ericsson r520: press menu, and press 5 — contact shared in just 1 second.
OP probably talks about the horribly slow and finnicky data transfer standard used on pre-earlier phones before Bluetooth was widely available and cheap.
Also, one project I did at a hackaton was a tv remote app with a couple IR leds connected to the original iPhone headphone jack and a webpage (no native apps at that point) that generated the correct signal in the form of a .WAV file for audio playback. Didn't win but that later landed me an interview at a top company.