Just buy the highest AX or BE number you can afford.

An AX6000 dual band mesh will outperform an AX3600 tri-band mesh if both of them are of decent quality.

Cannot remove the HyppTV. Even if you remove, TM will adjust back the price so that you still pay same amount. You either keep the plan or change to SWU plan.

Check your settings?

I'm just using the free DIR X3060Z and the tests were conduicted when the internet was being used.

Use fast.com and change your minimum test duration to 30 seconds and try again. Make sure you are near to the router.

Depending on network condition, Wi-Fi 6 may take some time to ramp up the throughput. On some devices or busy network, you will find that a 10-15 seconds speedtest is not long enough to reach the full speed.

Further explanation:
Wi-Fi 6/6e/7 use longer aggregates for data transmission, which means it can send more data at once before waiting for an acknowledgment (ACK). This approach can improve overall throughput but may introduce some latency in the acknowledgment process. If ACK frames take longer to be received due to longer aggregates, it could theoretically slow down the rate at which TCP congestion control ramps up its throughput.