Do you mean that you connect your pole hose to the Hozelock sprayer and apply the product through the pole? Do you not find that you are constantly pumping the sprayer manually?
I use Gardiners EZ-snap pole fittings, so I just (cut off the lance on the sprayer), and connected one of EZ-snaps to the tube.
Yes, I plug my pole hose into the sprayer and straight up through the brush and onto the gutter.
If you keep the container half filled, (or more), you only need a few (or slightly more) pumps to get the required pressure.
Obviously this does take some work, but (for me) I would rather this, than running out of battery on a back pack.
I just like to keep things simple these days.
It's lighter than a backpack.
It's easier to move around than a backpack.
It never runs out of battery.
And I hardly ever need more than 7 litres of degreaser to finish the job.
A bit of thick, cheap, bleach, added...always helps.