Just wanted to say that the readings on my new ic8 seems to be ok - not super accurate - but I think good enough if you don’t want to spend to munch on new gear and still have the option to do different apps than Zwift. On an amateur level I am happy with it and the results I make on events are ok I assume (I never raced).
So 250+ w is good travelling pace for me. 400+ w is sprinting for me. I won’t last for long. But yes, if you go into Zwifting only there is definitely gear to buy to get more accurate power readings and options on a controllable trainer.