There are numerous imix definitions floating around now, it really depends on who you ask. The more realistic ones define a pattern of different sized packets. And performance varies greatly depending on which imix flavour you use, which probably goes back to the earlier poster's 'dumpster fire' comment (although I don't know exactly what NPU generation they are referring to).

No line rate does not "imply pps at the smallest sized frames."

Network hardware always quote PPS using the smallest sizes. And this makes sense for things like route and switch processors. Perhaps you are confusing that.

You should reread your link a little more carefully. From your link:

">However it is also important to make sure that the device has the capacity or the ability to switch/route as many packets as required to achieve wire rate performance."

The key phrase there is "as required." Almost nobody needs to sustain forwarding Ethernet frames with empty TCP segments or empty UDP datagrams in them. In fact many vendors will spec for an average size. Since packet size x PPS will give you your throughput, if the average packet size is larger you need much less PPS to achieve line rate.