Is it in ericaceous soil? Pieris likes acid soils so maybe the soil it is in is too alkaline?

Welcome to GoY
I suspect the amount of water you have being given it isn't enough. were the leaves a good colour last year? if you are on alkaline soil give it a feed with a feed designed for camellias and rhododendrons. Up the watering, if you have the windy conditions we have it will need a lot more water than you think. Its best to water in the evening so the sun doesn't help evaporate it.

Assuming its in the ground, leave the hose on a trickle at the base for a couple of hours, moving it every half hour to cover the root zone. It takes up to two years for a shrub or tree to become more resistant to water shortage because only then will it have put out enough roots to seek further for water.

If its in a pot, give it a good five litres for the next few days, let the excess run away.

I gave it more water last night when I watered the garden, do you guys think it can still be saved at this point? As I said, all the leaves have gone but the flowers remain... atm!

You will only know if it starts to put out new leafy growth... keep it well watered during this dry warm weather particularly.

Thank you everyone :)