The original engine control unit (ECU) comes from a Camry or Rav, both relatively new models with a lot of extra features that my car doesn't have (automatic transmission, immobilizer, fuel system without a return line with a PWM-controlled pump, etc.). I would have to simulate all of those things so that the ECU doesn't have any errors in its memory or go into limp-home mode.
The new generation Toyota ECUs cannot be tampered with, as the CPU and memory are integrated into a single chip.
Therefore, standalone.
If there had been a standalone device with ODBII support, I would have bought it.
'However, the engine has 4 continuously adjustable camshafts, and since it uses a DBW (drive-by-wire) throttle, only 3 manufacturers offered solutions for that. These were Motec M600, Buhl Racing OBR euro6, and Vipec. None of them support ODB (On-Board Diagnostics), and Vipec was the most affordable option.' If one can consider 2000€ to be a reasonable price.
I checked about the TÜV (German technical inspection) beforehand: If the car meets the Euro4 emission standards and has an ODBII connector, it will be classified as Euro3 (possibly Euro4). Without the ODBII connector, it might be classified higher, but not as Euro3/4. The emission test report is not mandatory; it's at the discretion of the inspector. The standalone ECU is a different matter. It just shouldn't be too noticeable

.
'What I need is a simulator that can read various live values, such as oxygen levels and RPM, via the CAN bus.' 'It allows you to enter information like the VIN (Vehicle Identification Number) using software.'