Well not 8 litres and the hose is maybe a little short, but my favourite right now is the B&Q garden sprayer I got for £15.
It’s 5 litres but the spray is fine and lasts ages. Good pressure and a trigger spray wand. The hose isn’t too short but it’s not long so you may have to move the bottle or just sling it over the shoulder as you go around the bike.
I had a Hozelock one before from Halfords which was branded as a car washer, utterly useless for cars but ok for bike but it would only just cover the bike, yet was also 5 litres. The pump lock broke eventually so looked for another. The B&Q one looks cheap but seems fairly good quality. Hose attachment is at the bottom so risks leaking in the car like all the expensive powered ones seem to, but just ensure the nut is tightened, and check the washer in the attachment occasionally. They also do there more expensive Hozelock garden sprayers, similar litreage or some a bit more though they quote say 7 litres but says you can only fill 5 from what the box was saying. The cheap B&Q brand one says 5 litres and it fills 5.