I understand it is.... challenging to judge when the manufacturer doesn't specify anything, but would anyone have an order of magnitude estimate of the size of the capacitor in a DC block like pasternack.com/…

@user129412 Physical size or capacitance value? The physical size will be smaller than the dimensions for the unit given in the datasheet.

@JRE Thanks, I meant to ask for the capacitance value indeed. In my setup It'll function as a type of high pass filter (as there is some resistance to ground after the DC block) and I'm wondering what the cutoff frequency will be, more or less.

The capacitance value can be estimated from the given frequency range. That's a lower limit of 10MHz. Into a 50 ohm load, the capacitance will be at least 300 pF - assuming 10 MHz as the -3dB point of an RC filter.

But it could also be quite a bit more, I suppose. The lower limit is useful though, thanks for pointing that out.