The current regulations on pressure drop off are significantly more stringent than the appliances can handle.
That said, given that no has asked the simple and vital question of what the incoming pressure is should be used to gauge the quality of any advice.
Regarding the FHs refusal to allow the pipework externally. Is there an internal route through communal areas?
There is always scope for misinterpretation.
If my posts can be interpreted in two ways, one that makes you feel angry and one that doesn't, I meant the latter.
Everyday is an opportunity to learn something new.