Because this gets unanswered but the information available have updated since then, lets summarize:
Since 2019/2020 there is now a VCI replacement for the MUT3.
The original MUT3 is crazy expensive and the china clones are reported widely to be not be working properly and also stopping to work completely. Going the original MUT3 would cost about 1500$.
The protocol the car is talking is named j2534. Since over 10 years there is the adapter named Tactrix Openport 2.0 that works about 4 to 10 times faster then original MUT3 hardware. The Price of the original Openport 2.0 it is about 200$. Because the Openport 2.0 is out for so long, there are also rebuilds for about 10-20$ with free shipment. They are also reported to work, but if you plan to reflash your firmware of the car, then its recommended to use the original Openport 2.0.
This hardware is of course not detected as original MUT3 because its not a MUT3. But the user registered with the username
@kolyandex in this forum here wrote a driver to use j2534 adapters as MUT3.
The driver of kolyandex of course got hacked at some point by someone else that now sells his driver. Even this person who sells the cracked kolyandex software recommends to not use china clones for really crtitical operations here:
https://mhhauto.com/Thread-MUT-3-J2534-FULL-DRIVER?pid=2406799#pid2406799
Here you can find the forum of kolyandex discussing about the MUT3-driver :
https://forum.kolyandex.su/viewforum.php?f=14
kolyandex also reverse engeneered the BMU and EV-ECU of the imiev:
https://forum.kolyandex.su/viewforum.php?f=22
The latest version 2.2 from 29.02.2024 of the MUT-3 driver and the attached ECU modification tool have added many benefits for the imiev that have been developed since version 2.1 (05.12.2021).
kolyandex seem to have changed the licensing of the driver since 2.1. In exactly version 2.2 there is now mostly a usb-dongle required to run it. This adds at one side the benefit to be able to reinstall it on any hardware you like and to run MUT3 software with the driver in a virtiual machine (licencing in a virtual machine was not possible before).
Back to the main topic:
Yes, it would be nice to have even a hardware replacement for the Openport 2.0 build by an arduino, but getting a china clone of the Openport 2.0 for about 10-20$ would cost about the same as an arduino setup with MCP CAN transceiver and so on. I do not think it would make sense to change anything on the hardware side.
Of course it would be awesome if someone could release a opensource driver for the MUT3 support. I think this is the part now to go further in the as free as possible MUT3 solution. Maybe at some point kolyandex would opensource the MUT3 driver by himself? It currently does not look like kolyandex is releasing much or any opensource software, but lets not loose the hope about that.