Correct
Nothing is as effective as being able to wash it at all
I use the IK Multi. It's pricey at 100 odd, but you can also get one which foams and is powered - that may be a good compromise for you between a foam cannon and sprayer, but the powered one is even more expensive.
The IK MULTI Pro 12 + sprayer is characterized by maximum performance in terms of ergonomics, ease of use and safety. It offers a professional spraying solution to achieve optimal results in a wide range of sectors such as construction, cleaning and disinfection, virus, pest and epidemic...
www.cleanandshiny.co.uk
The IK E Multi Pro 12 is a Battery-operated sprayer, manufactured under high standards of quality, robustness, reliability and safety. Must be used with chemical agents with surfactant properties (surface active). The Battery Compressor Pack includes: The 18V Ion-Lithium battery with charge...
www.cleanandshiny.co.uk
DW10 will give you 10% off over a certain amount.
The one you've linked will be absolutely fine, but worth seeing if you can get a larger container than 5L. This looks alright, though haven't used it myself:
https://www.prokleen.co.uk/pro-kleen-garden-pump-sprayer
It mentions it deals with patio cleaner, which will be a strong alkaline - therefore I'd imagine it'd be safe to use with Touchless.