Questions about Hiker Pro

This should fit. The entire filter unit is replaced.

No, that's definitely not possible.
I just disassembled my part to be absolutely sure.
The filter only goes up to 750 litres, and that's about the capacity of the activated carbon.
The whole filter can be replaced, of course.
My secret tip - this is the filter I use now, which is ultra-light and highly effective:
Combine these two parts:
Care Plus water filter