The QSGMII signals in this blog are very high speed. Beyond the range of what you can measure with budget tooling. Even the probes for such lines are thousands of dollars.

There are some budget sampling oscilloscopes on the market, but budget is still mid four figures and up. That's before probes, cabling, and other things you'd need. Sampling oscilloscopes are only useful for repeating test patterns sent by SDK tools, not for capturing normal data as it goes by

It's possible to look at Ethernet signals with oscilloscopes in the budget range but you would need appropriate fixtures to tap the line. Even at those speeds, touching a regular oscilloscope probe on to a wire disturbs the circuit so much that it might stop communicating.

At the other end of the scale, looking at classic 10M Ethernet signaling is perfectly doable with a sub-$1k scope, and 100M should also be fine with anything 500MS/s or higher. Note that Cat5 is rated for a bandwidth of 100MHz.