Seems the canbus mod is reasonably simple. It is only removing a few resistors and having the g4 firmware.   The catch is resistors are physically small. I’m guessing 0602 sized which is 1.6x0.8mm. A couple are also in a row packed together so access is a bit restricted.   Link obviously recommends you use soldering tweezers or two irons to heat both side at the same time so it has less risk in ripping the thin copper pads off the board.  They also recommend static protection which is normal. I’d note that usb powered soldering irons are also extremely dangerous for this a kind of work. Battery ones that are USB charged are fine, just not any that are connected to the wall socket while in use.

I saw this, which is why I asked… https://forums.linkecu.com/topic/17552-linkplus-g3-canbus-modificationenable/ and this… https://forums.linkecu.com/topic/14013-g3-with-g4-firmware-dash-compatibility/   A digital output or serial port could drive a canbus controller if the software allows.    You can get both controller and transceiver on a custom board for about $10 these days if you don’t need fault tolerance FD. 

AFAIK (G4 owner) the CANBUS support came along with the G4+.   G3 could be software upgraded to be largely G4, G4 can't be upgraded to G4+ sadly.

What did link say about canbus on g3 with g4 firmware?

I did, but nice ones were double what we paid for the Levorg, and already having a Golf I know what they cost to fix so not worth going for a cheaper one which is still at the edge of our budget anyway.