There is spec on heater pump on how low inlet pressure can be. Many known brand has no problem I believe.

My house all shower are direct supply just as kitchen sink. It is originally from developer. The pump at the tank is good because you will have good pressure overall. How powerful the tank depends on how many tap. Low power might not produce good pressure if many taps are opened at the same time.

Inverter type will provide constant pressure and no water jetting effect. Remember that good water pressure means more wastage because more waste water

If you just need for shower, then just go for heater with pump, but I think the sink tap also low pressure right? This is my problem too I was planning for tank pump years ago until now

Pump would not has significant increase on electricity I believe.