Working on designing and building an interface to properly integrate a modern phone with Toyota/Lexus infotainment systems from before 2010 (which are using the proprietary AVC-LAN protocol).

I've explored all existing commercially available solutions and none match my requirements/standards (high-quality audio codec/DAC, USB-PD, steering wheel controls, no splicing or cutting into the loom, no cutting up the dash, etc.).

After researching how the Toyota/Lexus infotainment systems work I found they are highly modular, and actually quite easy to produce custom modules for. The proprietary AVC-LAN protocol is well-understood, and actually makes it really easy to integrate with. The display are just NTSC composite, and touch events (in fact, all button presses, including steering wheel media controls) are emitted on the AVC-LAN bus.

An simple board with some interfacing logic, a DAC and an RPi nano should be all I need to allow good Bluetooth audio integration, and lossless audio via wired USB, both controllable from the steering wheel. You could do all sorts of fun things with the display (such as displaying vehicle status from ODB, lap timer, G-force meter etc.). If I use a RPi compute module then running Android Auto should be quite feasible.

It's just a hobby project though, I'll probably open-source everything. Not planning on commercializing it.