Thks for this. Pumps can be smaller capacity if judiciously connected to needed outlets that require the desired flow rate.

This can also be achieved during renovation, where the plumbing for WC inlet refill are separated in each bathroom from cold supply to each bathroom. A separate dedicated distribution pipe of sufficient diameter and slope and an appropriate reducing (e.g. 1" or 3/4"  to 0.5") outlet to each WC should offset the pressure loss and yet achieve satisfactory refill time though not as fast as the pumped assisted rate. This also avoid water hammer issues or leaking toilet refill valves overwhelmed by persistent and eventual wear from pump pressure. The inlet point at the wall will of course terminate at a higher distance from the toilet floor eg 12-24" vs the usual  6-12" which is shared with the cold plumbing line to basin or bath/ shower depending on bath layout. It also avoid the nightmarish scenario of a leaky flush valve that will empty the tangki in minutes and causing the pump to run dry but some models will have dry run protection.

Combine this with low flow rate but high pressure wash basin aerators and shower head e.g. Takagi Kimochii or the 200 holes Korean fine spray type, the required overall flow rate can be reduced somewhat thus allowing a smaller pump with that flow rate to be used.