I'd expect there to be three rough tiers of equipment:
1) IMPSTAN, fully certified. Obviously conforms with all operational requirements (power, user interface, control systems, etc.) and also meets high standards of reliability, testability, ruggedness, fail-safe behavior, and so forth. Tends to be very expensive, but well worth it if you need gear you can trust.
2) IMPSTAN-compatible. Designed (and perhaps guaranteed, for some legal or other value of "guarantee") to interoperate with IMPSTAN equipment, but not certified, and not necessarily meeting the same reliability and other secondary standards mentioned above. Depending on the particular supplier and device, this category can range from "just as good as IMPSTAN at a quarter of the price" down to "maybe we can use it as an anchor".
3) Not IMPSTAN compatible. Most often found on worlds (and in regions) that entered the Imperium with existing TL8+ industrial infrastructure. There will be a profitable market in adapter devices between local and Imperial standards.
Regarding the third tier, it's remarkable how resistant tech choices are to change once they've turned into infrastructure. See e.g. left- versus right-hand drive cars, rail gauges, electrical voltage and frequency, broadcast TV specs, and so forth.