Re. equipment (generators and passives) needed (I only checked for the 465):
- For adjusting the Hi-Z step attenuators' frequency behavior, the 1 MHz CH1 and CH2 inputs need to see a 20 pF capacitance. A 20 pF "normalizer" is needed with many people using their "reference" 10x passive probe, hoping it's set to about 20 pF or at least away from max or min capacitance. Source is a 1 kHz square wave generator. As you say, very lax requirements there.
Since adjustments need to be made up to the 5 V/div setting, a relatively high-amplitude, "good-looking" square wave is needed, especially when using a 10x probe. Normally, the high-amplitude output of a PG506 is used, with fixed attenuators as needed. Wave front (HF) and flat top (LF) are adjusted this way.
- A 50 kHz sine wave is used for determining the base deflection against which the BW is measured. I'm sure that 100 kHz would be no problem so 100 kHz and >=100 MHz from the TinySA may be used. Voltages up to 2 Vpp, so no problem for a TinySA. Just an SMA-to-BNC cable and 50 Ohm feed-through needed.