I’ve used one of these in the past which looks similar to the products you’re considering and I found it quite poor compared to my pressure washer snow foam lance;
CleanYourCar - Foam Cannon The all new Foam Cannon Wash gun is a fantastic addition to anyone's detailing arsenal. Our Foam Gun is constructed with high quality brass fittings and tough plastic body connects directly to a standard hoselock hosepipe connector and precisely mixes a shamp
www.cleanyourcar.co.uk
Edit; Oops!
; I’ve just realised they’re not similar to the Foam Cannon at the link I’ve posted above, as the products you’re considering have a pump to pressurise the canister holding the snow foam.
My experience of the Foam Cannon was that it left a very thin, watery solution on the car even with a strong snow foam to water mix ratio, and I found the solution pretty much ran off the car as soon as it was applied (little to no ‘cling’ at all). By contrast, snow foam applied using my snow foam lance and pressure washer leaves a much thicker foam on the car, which clings, loosens the dirt and then slides off after dwelling for a few minutes as it’s intended to do.
If you were planning on getting a hand pump pressure sprayer, then a cheaper alternative to consider might be a hand pump garden sprayer like those at the links below (there are many other sizes / brands available); cheaper than the foam sprayers at the links you’ve posted and if the garden sprayers don’t work particularly well, you’ve not spent lots of ££££’s on something that doesn’t do what you want it to, as you can always use it in your garden to apply lawn treatments, moss killer and weed killer etc.
. I used an 8 litre garden sprayer to pre-soak before washing my car and to rinse after washing it during a hosepipe ban a few years ago. It did a decent job, the only real downsides were 1) the small size of the nozzle on the spray wand meant it took a while to pre-soak and rinse and 2) having to keep re-pressurising the pump quite often to maintain the water flow.
Order online at Screwfix.com. Pressure sprayer suitable for a variety of gardening applications. FREE next day delivery available, free collection in 1 minute.
www.screwfix.com
These days I don’t snow foam my car before every wash; only on the rare occasions it’s dirty enough to justify it, and I don’t really let it get very dirty. Normally it just gets a pre-rinse using hose on high pressure setting before doing using a ‘safe‘ 3 bucket method wash.